4a-ge intermittant backfiring and missing

[skit]

Hi all,

I have searched through the archives but didn't find anything of great use.

I was at oran park 2 weeks ago and after the 2nd session i went back to the pits, car was running fine. When i restarted the car, it ran like a hairy ass - firing on 3 cylinders, sometimes only 2.

We fiddled with everything through the day and couldnt come up with a solution. But the strange thing is once the car starts up ok (maybe one in 10 or 15 attempts), it runs fine - until you turn it off and then try to restart it.

I had not touched/changed/fettled with anything at all under the bonnet when the car started doing this. So, we set about testing different things, starting with the basic stuff.

To date I have replaced (to no avail)

dizzy rotor button
dizzy cap
all dizzy/coil leads
spark plugs
tested fuel supply to rail (good)
switched ecu's
switched coolant temp sensor
switched map sensor
checked all earths
replaced entire main fusible link box off battery (+) terminal.

I thought I had cracked it several times. Two of the triggers in my old dizzy cap were broken, my dizzy had some residual oil in it, there were metal filings inside the cap too, and some corrosion in the terminals. One of the copper fuses in the main fusible link box was so badly corroded its a miracle that it even conducted any current, and the car won't run at all without this fuse. And an earth strap was bit on the suspect side, so I redid it....but no try.

I found an old post by mike86 in 2006 where he had hard wired his dizzy with some wires mismatched and had similar problems with the car running terribly at randomly intermittant intervals. However, as I said, I have changed nothing to instigate the onset of this problem.

I am getting a little frustrated, my other thoughts to continue the elimination process are to change the:

coil
ignitor
tps
injector time sensor
air temp sensor

I realize the cause of the problem could be a multitude of things, but I'd be keen to hear people's experience with random sensor/electrical components failures and their effect on how the engine runs.

Cheers
Scott

[nath]

does the car electrics die aswell like when u put the foot down it kills the radio,lights etc then restart every thing normal

[skit]

does the car electrics die aswell like when u put the foot down it kills the radio,lights etc then restart every thing normal[/b]

nath - no, the auxilliary electrics remain fine. When the car is running poorly, you can can open the throttle wide and the revs will not climb over 800rpm no matter how long you wait. The occasional backfire happens at WOT, whereas at idle it just chugs away on 2 or 3 cylinders. This back firing may indicate a lean condition - but there is good fuel pressure to the rail, which leads me to wonder if it is a fuel injector control issue.

I should add that the ecu is not generating any error codes either.

[sprintdaddy]

Have you checked your timing and check your timing belt as well

[Javal]

Edited:

Did not read symptoms correctly.

[nath]

when was the last time you change the fuel filter

you might be getting pressure but not enough flow

just throwing ideas

[SLO-030]

when was the last time you change the fuel filter

you might be getting pressure but not enough flow

just throwing ideas[/b]


I agree with that.

But also it sounds alot like a coil/ignitor problem. Have you checked spark at all leads?

Also while it is running like shit start by taking one injector plug of at a time. You will hear the deffernce wether its missing on that cylinder.

As far as it sounds like its electrical not mechanical so to me BHG is out of the question

[skit]

Guys,

Timing and belts are fine, like I mentioned the car will run fine sometimes, which leads me down the electrical path, rather than a mechanical problem.

Would a BHG show these symptoms?

I will replace the fuel filter tomorrow, i suppose is it possible that it may be blocking/flowing/blocking.

I have already replaced all spark leads, am trying to borrow a coil and ignitor to test. I took out my coil & ignitor today and went shopping, but no-one could offer any aftermarket ignitors, and no-one had a coil in stock (bloody central coast shops....)

I will haven't popped each injector plug off so I will try that too.

Cheers for the help, will report tomorrow.

scott

[Matt-AE86]

Change your coil. The coil could have a hairline crack or something and be not firing correctly. This has happened to me. Also change to another ignitor. I guess you can do both of these at the same time.

[Javal]

Guys,

Timing and belts are fine, like I mentioned the car will run fine sometimes, which leads me down the electrical path, rather than a mechanical problem.

Would a BHG show these symptoms?

I will replace the fuel filter tomorrow, i suppose is it possible that it may be blocking/flowing/blocking.

I have already replaced all spark leads, am trying to borrow a coil and ignitor to test. I took out my coil & ignitor today and went shopping, but no-one could offer any aftermarket ignitors, and no-one had a coil in stock (bloody central coast shops....)

I will haven't popped each injector plug off so I will try that too.

Cheers for the help, will report tomorrow.

scott[/b]

BHG would not show the symptoms you have described. I was a little bit tired when i made that post, so it has been edited.

As others have said, replace:

Fuel Filter
Coil

SHOULD do it.

[skit]

Thanks for the input guys.

Have tried a different coil / ignitor combo, no success.

Just picked up a new fuel filter, will try it this arvo. sigh.....

[ae71neo]

Hope you get it fixed man, skids are only a few weeks away.

[skit]

Hope you get it fixed man, skids are only a few weeks away.[/b]

Thanks man, yep we'll sort it out. Running out of things to try.

Car should have some extra goodies by then too, can't wait.

[skit]

Tried a new fuel filter, didn't help.

Next I will do the injector time sensor and air temp sensor. I had been trying to avoid the injector sensor because it's a pain to get to between the firewall and the back of the head. I wouldn't expect faulty sensors to create the problem, but who knows?

[Blood Child]

i'm having a similar issue atm. i'll let you know what it is when i get it sorted.

[Matt-AE86]

I think you will find that's not an "Injector Time Sensor" its actually a Water temp sensor to ground the Cold start injector only when... its cold! The other is a water temp sensor for the ECU which richens/leans the fuel considering the water temp. Other then that.. Bad grounds ?!

[skit]

I think you will find that's not an "Injector Time Sensor" its actually a Water temp sensor to ground the Cold start injector only when... its cold! The other is a water temp sensor for the ECU which richens/leans the fuel considering the water temp. Other then that.. Bad grounds ?![/b]


Yep that sounds right Matt, I think the toyota manuals refer to it as a " injector time sensor" though. I don't think it would be be causing the problem I have.

Having said that, my freind (also a toyota mech.) had an ae82 twincam with a dodgy water temp sensor. With the sensor unplugged, the car would run satisfactorily (far from perfect though). With the sensor plugged into the harness, the car would randomly misbehave in a similar fashion to mine at the moment. However, when I disconnect my water temp sensor, my car doesn't seem to start.

I wouldn't have thought that the a bad sensor could confuse the ecu so badly, but we've seen it first hand so..... wish I could speak to the toyota guys who programmed it!

Anyhow I have two spare sensors here. I will do a resistance test on them in a cup of water to check they're ok and then put them in.

Car will have ITBs very soon, but I want to solve this problem before switching to them. I will be happy to junk the cold start & TVIS crap when I remove the standard T/B and manifold.

[muncher]

I know I'm grave digging here but did this ever get solved, I'm having the same problems, car runs fine and idels ok then u turn it off and start it up again and it misses/runs shit wont & idel, smells like its running heaps rich..

I was thinking TPS, Timing maybe??

[cuzzo]

Could be leaking injectors.

[muncher]

Nah I'm fairly sure the injectors are ok, I just can't understand why it runs ok sometimes, eg. idles fine doesn't pop and shit and other times it wont idle and runs really ruff, it will still rev smooth but wont idle, and when you back off it surges the whole car.

Also when cranking it over, it will crank fast sometimes, then u go again and it will crank slow and fast slow/fast.

Battery is brand new, 470cca so that should be more than enough.

I'm fairly sure the timing is out but I set it how you are meant to dizzy out line up everything back in.

found today that where the map sensor vac line plugs into there was a empty port next to it, that was sucking in air, looked at some other photos and its always blocked off, so might try that tomorrow and see how it goes, also need to find the wire that the O2 sensor goes to as that is not plugged in either, could also be the course?

[stylz]

keep us updated with your progress. I'm interested in knowing whats causing the problem
sounds like a really annoying thing to have happen :/

[muncher]

will do, I'm taking it in soon to get the TPS, timing checked.

I was looking at the pinouts on club4a.net there was a wire that was ?mrkd but it also said computer memory? I was wondering if the computer is completly loosing all power and had to reset each time it started could this be the problem if one of the sensors is playing up.

E.G. tps was just out. Sometimes the computer will accept it and sometimes it wont?? I'm not sure if thats how they work as I know jack about ecu's but just a thought.

[Nikkojoe]

All the tps does is control when the engine goes into idle loop (ie when throttle is fully closed so the idle drops to decent levels).

Unplug the tps and see how you go. Doubt its the cause of your problems.

Also check all earths on the engine to the chassis, the ecu/loom earth which is bolted to the inlet manifold near injectors, make sure map sensor plug/ vac hose are in good order. Unplug air intake temp sensor (round yellow plug on inlet manifold) and see if it works better.

[mikewestphoto]

bro, tps does more than that.

It's not the batt/memory wire, I've seen ecu's wired so that the batt and ign wires both get power at ign, dodge but works.

Could be tps, might not be tps. in my case, it was. it would short out causing the engine to miss and idle like shit or just die.

Smelling like fuel occasionally probably isn't timing related, more to do with a cylinder/s not firing and throwing the fuel out the exhaust. Check components to do with spark, borrow someone's ignitor and coil if you can.

when it's idling shit, restrict the return line and see if it gets better. Although it's probably not the regulator as you say it smells like it's running rich, a dead regulator would cause the engine to run lean.

[muncher]

I've currnetly running a newish ignitor+coil that came from a working car so that should be ok,

When I disconnect the TPS it dies straight away, I might try swaping another one in there and seeing if that helps,

The yellow plug you mentioned, is that the amibient temp sensor? I don't have this conneected as there is no plug for it, although there is a random plug that has a gree connector floating around in that area. maybe I need to get a plug for it and swap it over?


One other thing that could be related, is when the car is turned off after running for a while, it will leak fuel out of the breather hose at the engine bay end until you realease pressure from the tank (taking the petrol cap off) Why is that happening?

Cheers

[Nikkojoe]

Is the return line using the old charcol canister line? If it is, then at the tank end, swap the charcol canister line with the old 4mm return line at the tank end.

The engine should not die with the tps disconnected, I would be thinking something along the lines of map sensor if this is happening

[muncher]

i got a map sensor from Kaizen Garage on here... I'm starting to think that it would be easyer getting a complete new loom and starting again. I really need my car running by monday.. which it wont be, so I'm really out of ideas.

I think i'll just dump it at an auto electrician and get them to sort it, it's really pissing me off.

[Nikkojoe]

Check the connector of the map sensor. My plug on the loom side had one pin dislodged so it never made contact and the engine ran in limp mode (lots of missing, would not rev above 4500rpm, really really rich). I tried other map sensors but since the loom plug was the problem, changing the sensor had no effect.

Also try to see if the map sensor hose is cut.

Also if i disconnected tps, the engine would stall.

[muncher]

i've replaced the map sensor hose, checked the plugs seem ok.

it still will rev and so on, but will run very very ruff

got it to just idle, its still very very ruff I could swear it's the timing, but if i play with the dizzy (swing it up and down) it has no effect.

[skit]

I didn't "solve" the problem I had. I eliminated it by removing the harness & going to aftermarket management with new wiring altogether. That was after changing/testing everything and having no luck - map sensor, water temp sensor, tps, coil, ignitor, air temp sensor, fuel pump.

However, when I took the old harness out and had a close look, one of the wires going to the dizzy had severed. I'm not sure on the exact function of each wire, but my guess is that this wire was sending a reference back to the ecu from which it was sending the firing & injector signal ouputs. If the reference signal was out, I imagine the result would be the odd behaviour I experienced.

stripping the loom is a pain unless you take it out, but maybe it is worth checking. Possibly a wire has broken around the oem dizzy harness plug.

[wide s13]

i had this problem just this week after swapping motors. I swapped dizzy for another one and works fine now?
but make sure its the dizzy for your motor (bigport/smallport etc)
as that was my problem.

[muncher]

tried two dizzys.. have one with the heat shield? thats the correct one for a rwd jdm 4age yeah?

Also what should the marks look like on the inlet and exhaust manifold pullys ? becuase mine were a little bit offset maybe this would be the cause??

I've found out that its filling the cylinder with fuel, when u crank it it gets like a hydaulic lock (or what sounds like) and fouling the plugs all the time, even when u take the plugs out clean them, dry out the cylinders put eveything back in... it still don't want to fire???

It has to be timing... it has to be haha, well with this f*n car it could be n e thing, would you reccomend I try a new (second hand off here) loom??

I'm thinking of going down that path...

[wide s13]

thats what mine was doing so i wacked my old smallport distributer in and it was fine lol
i don't know if the different?

I lined al the marks up to top dead centre put my dizzy in so i have equal adjustment then cranked her over.
and shes going now still lol

[muncher]

got it running sort of, seems still to be overfueling a bit, have found a melt in the loom, seems to be the cause of the problems we are having.

[muncher]

well its not a melt.. its now running and still shiting about, eveynow and then it will run sweet peform really well, other times runs really shit.. can't work it out..

Might try a new loom + computer

[muncher]

ok, have got it running timing spot on.. without the map sensor. when the map is plugged in, it throws the timing out heaps..

would that be a crook map? or wiggity wack wiring?

[SLO-030]

If the map sensor is doing that i would say its the map... The map sensor controls timing in a way as well as the injectors.

Replace the map and go from there

[muncher]

It does seem a chance. Is there n e difference between the fwd and rwd / jdm and adm MAP sensors? or are they all the same deal?

[muncher]

Well, the car was running with out the map sensor, not well mind you but running. I've found out that i've got a fwd loom + ae82 computer.. And the more I think about it, how possibly can the car run with out the map sensor plugged in?

I'm going to start again with the wiring, get a full JDM loom + comp and start again.. I'll try another MAP tomorrow, but I doubt it will fix n e thing, the car is cursed I tells ya. :s

UPDATE, the car will now not run, I put my heat shield back on the dizzy and relocated the earth strap so it didn't run across the extractors... went to start.. no good, so I put everything back to where it was and still no good. What the f*** !!! I can't work it out... It's got alot of people stumped.. I hope to hell that the new loom will sort shit out..

[Nikkojoe]

Engine can run without map sensor, it just runs in limp mode.

One of the things i found is that the car wont start cold without a map sensor if the tps is plugged in......

[muncher]

hmm, my tps is plugged in but the connector is a bit dodgy + we had to swap and change plugs from the rwd loom ...

I think the new loom will sought out a few of my problems

[muncher]

OK..

Car is running BUT with no MAP or TPS or cold start injector. So it runs, but very shit. Missing alot, running very rich.

When the MAP is disconected it will run.

With the MAP and TPS disconected it will run.

With the the MAP and TPS pluged in it won't run.

With the MAP disconected but the TPS plugged in it will run.

Plugging in the TPS or disconecting it with the MAP disconected, it don't make any difference.

Can any one tell me what the hell is going on?

NOTE, swapped to different MAP sensor off a working car, did not make any difference, it still throws the timing way out each time you plug it in.

[muncher]

<div class='quotetop'>QUOTE </div>
If its ae82 bigport loom it's has the same wiring to the ecu as a rwd loom (same injectors, tps, map sensor etc). AE92 bigport (s1 ae92) has the round tps plugs, different injectors (small port ones) and ecu is not backwards compatible with other bigport looms.[/b]

Quote from Nikkojoe, that has explained my problems, I THINK.

slide86 and I had to modify this loom so I guess its a AE92 loom and I have ae82 computer thus making them non compatible.

So I guess that's why it will run with no sensors but stop when they are plugged in, RWD loom + comp coming soon so I will keep you updated if it solves my problem or not....

Thank you Nikkojoe!

[Andor]

Holy crap, from the sounds of it I have the exact same problem as you. Mine runs like shit, keeps stalling. Unplug the map sensor and it's all good. My loom was made from scratch by toyospares and was running fine for 2 years. So i dont know about your loom/ecu theory. btw mine is an ae92 'redtop' bigport tvis motor with matching jdm ecu.

[Nikkojoe]

<div class='quotetop'>QUOTE (Andor @ Sep 18 2008, 05:30 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=589991)</div>
Holy crap, from the sounds of it I have the exact same problem as you. Mine runs like shit, keeps stalling. Unplug the map sensor and it's all good. My loom was made from scratch by toyospares and was running fine for 2 years. So i dont know about your loom/ecu theory. btw mine is an ae92 'redtop' bigport tvis motor with matching jdm ecu.[/b]

Do you have the part no. on the ecu? Ive got a redtop bigport ecu in the garage and matching loom.

Muncher: I dont see how the ecu would work with the ae92 loom. The wiring to the injectors are on different parts of the loom. One thing that you will find is that the intake temp sensor on an ae92 bigport is in the airbox, not on the intake manifold (ae82/ae86 4age, round yellow plug on intake manifold). So if you are missing the plug on your loom, you probably have the wrong one.

Also, ae92 looms have a knock sensor, so make sure you have that hooked up :)

[muncher]

it's a 93 modifted loom ( i think), me and huw had to change the TPS and injector plugs and something else I forget, it also has like this metal box type thing that if it's not plugged in the injectors won't work.. do you know which looms have that?? I can take a picture if you don't know what i'm talking about...

Anywho, the car will run, but it will take a fair few cranks to get it going then it will miss and shit around and won't run with the map plugged in. TPS makes no difference..

It has to be loom + comp combo is wrong, hence my sensors won't register??

Still waiting on a loom and comp from Japan damm it! Nikko you don't have n e bits do you?

Cheers

[Nikkojoe]

ah yep, you have the ae92 bigport loom. TVIS plug is also different. Ive got a complete untouched ae92 bigport loom, ecu, injectors, injector resistor, tvis plug, knock sensor, tps im not using, although im not sure if im gonna sell it as of yet.

Whats the part no. on the ecu? Ill compare it to my ae82 bigport and ae92 bigport ecu. Have you got the knock sensor hooked up? If you dont, ecu will put it in limp mode.....

[muncher]

I definitely have an ae82 computer. I checked the numbers on club4a, and from what you are saying I have an ae92 loom. You said that these two items are non compatible.

Thus causing my engine to not run with any of the sensors hooked up yeah?

If it is possible to run these two items, then I don't think I do have the knock sensor plugged in. If I plug the knock sensor in will it allow me to run my MAP and TPS as well or are they unrelated to the knock sensor?

[Nikkojoe]

But as ive said before, there IS NO WAY it would start. The injector pins are different!!!!!!

Also, can you tell me the part no. of your ecu? Is it 89661-12250 or 89661-12080?

[muncher]

what do you mean injector pins? We had to chage over all the injector plugs and run that strange looking metal type box to make the injoctors pulse.. would photos help?

89661-12080 thats mine

[Nikkojoe]

Umm, injector pin outs on the ecu are different positions. If anything, you are running on 1/2 a bank of injectors......

I would not be running that injector box (technically called injector resistor) if you are using ae82 grey square plug injectors. Basically that resistor pack has 1 ignition wire and 2 injector power wires coming out. Remove the box and join all those wires together.

[muncher]

Its ok now, Im getting rid of that loom and comp all together, thanks to huw I've got a rwd loom and comp now, should be fitting it up tomorrow yay, I'll tell you how it goes

[Nikkojoe]

Actually, dont worry. They do have the same injector pin outs (club4ag list them wrong).

I think the problem is you running the resistor pack on bigport injectors.

[muncher]

we hooked up the JDM loom + comp and now have spark but no injector pulse (hooked up a noid light, spelling?)

We powered the big yellow wire, and the coil obviously has power but still no pulse. I was looking at the pin outs and it said something about a blue trigger wire, is this the one?

BTW my old loom+ecu+resistor combo ran the car just not well/in limp mode lol! and as soon as we plugged the map in it would throw the timing out, with out the resistor pack the injectors would not pulse. ! my car is cursed I tells ya

[Nikkojoe]

earthed the loom?

Do both pins of the injector plugs have 12V on each side? Made sure both black/red (+B and +B1) wires on the 3rd ecu plug have ignition to them, and constant battery hooked up to the red/white (batt) wire?

[muncher]

Will double check, yeah we have earthed the loom in the factory spot, + have 2 decent sized earth straps off the battery.

Will double check all those wires today.

I'll let you know how I go.

[muncher]

Running out of ideas,

It SOMETIMES has spark, sometimes strong then weak then nothing at all..

it SOMETMES has injector pulse, always weak.

Umm do I have a wrong part? MAP should be ok, TPS part number I have is 89452-0131, ECU 89661-12051 with matching jap loom, coil w/igniter - 19070-15120 70 Dr

The loom is earthed in the factory spot on the intake manifold.

[tony_kim]

<div class='quotetop'>QUOTE (muncher @ Jul 25 2008, 06:48 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=566720)</div>
it still will rev and so on, but will run very very ruff[/b]
will it stop reving at a certain RPM point ?? (ie low)

if so it may be TPS related.

[muncher]

No no, it won't start now, I've changed over looms from an ae92 loom that would run it but in limp mode, i.e. run shit, rev ruff, idel hell lumpy, no power. to a JDM rwd loom and computer combo which should run it as my engine is a jdm rwd bigport, but no luck. Problems discribed as above,

<div class='quotetop'>QUOTE </div>
smallport and bigport injectors should all be low impedence, ie. have a resistor pack. I believe you will find it by tracing the non-black wires (red or white on my loom) from the injector plugs back. It will be a small unit probably bolted to the strut tower originally and feeds live power via the coil/ignitor. I think the injectors are 2.7 ohms?[/b]

Found that in my searching, is this true? it could explain my low pulse now in the injectors? Maybe I have the wrong injectors, the guy i bought the engine off has been no help so it could be a shonky put together engine pack? Do I need to wire in a resistor pack? if so where?

[Nikkojoe]

What injectors do you have on the engine now? Grey/square plugs? If so, they are what you need.

Try changing the spark plug leads (my old ae82 4age would not start cause the leads were stuffed, had weak intermitant spark).

And how are you measuring the pulse of injectors?

[muncher]

ITs ALIVE... long story can't explain now, will later in detail.. all sorted!! thanks heaps for ya help tom.

[biggo]

do tell

[muncher]

Ok, first and foremost the main problem that we had was timing.. Sound simple but no.. never is, the timing we set to run the car on the ae92 loom (which was done by a 'mechanic') would run the car but in limp mode as there was no knock sensor + ae82 comp (non compatible apparently) + probably a whole lot more issues with that loom. I brought a proper JDM rwd loom from an ae86 and the computer to accompany it.

With this loom the timing seemed to be a fair few teeth out so played around with it until it fired.

Other problems we encounter:

- The factory earth position had the wrong bolt in it and was not maintaining a decent enough ground to earth out the ECU

- Had to power the 'big yellow' wire that powers the injectors

- had to strip the loom down and check for splits/weak connections, found one on the cold start that leads into one of the injector plugs + cranking wire..

- Due to the earth problem wires were getting power that shouldn't and things were all over the shop until that problem was sorted...


in conclusion, earthing and timing were two main issues with the dramas.. Triple check the simple things before you advance on to the more complex.