LIMP MODE

[Mr Fujiwara]

hey guys,

sorry to start this up again, i thought i would start a fresh thread since the topics kinda changed a bit compared to a few months back..

over the last few months, ive been trying alot of things with my car.

i will recap info about my car, charataristics of driving etc.

Car is a ADM sprinter with a JDM 4age with un-molested loom and matching ECU

1. the car runs SOOOO rich, did about 90km to 3/4 of a tank
2. the car makes a lot of torque betwwen about 1500-3000 (don't have working tacho but at about 30km/h in 2nd gear)
3. the car revs and sounds normal with no load on the engine (in neutral)
4. the car struggles to rev over about 3000 and makes a lot of noise and doesnt go any faster.
5. i just went in a JDM 4age yesterday, and it actually revs and makes power higher up, which mine does not.


is it safe to assume my car is in limp mode, as a few people have been telling it isnt.... :blink:


i can rule out Map sensor as i have bought a new one and tested it, the TPS seems to be working fine, timing is fine, changed the plugs, it made it idle better thats is...

i bought an AW11 dizzy cap, i had to actually drill a hole next to the orginal one which i didnt like doing , but it sits on straight and fires normally and idles even better, but that is is ONLY improvment.

this car is not running an 02 sensor also...(but i am told it shouldn't make to much off a difference, just make crappy fuel ecconomy.

next I'm about to get an ignitor and coil, but i also fear this will have no improvment, so i ask you experienced guys for help again.

then i was thinking about my knock sensor, and is there any way to test if this is working correctly?

Also i went to toyospares in melbourne, and the guy there said "well if you don't have all your factory sensors your ECU's gonna say FUCK YOU i want my facotry imputs and will go into limp home mode, so get a O2 and then it will work"
but I'm not intirely sure that would be the case...

so any imput here would be a great help, ive been saving money lately and if its not working in the next month or so, I'm just going to rip out the loom and either go twin carbs coz i can't be stuffed with EFI, or I'm going to go all out and get Aftermarket ECU and get it all hooked up and tuned..but hardly worth it if my engines remaining stock anyway.....

thanks

[Nikkojoe]

There is no knock sensor on a rwd jdm 4age. And i agree that your car is in limp mode, exactly like mine was when the map sensor was technically not connected.

I can't remember if you did this last time, but on the map sensor connector plug, check that all pins are not pushed back and all should be the same level. This is actually on the loom plug, not the map sensor plug. I swapped my map sensor with a mate and it made no difference(because it technically never made any connection). Check the continuity of all the pins from the map sensor to the ecu to see any breaks in connection.

I'm fairly confident that its the map sensor/connection to, there are not really any other factors that will affect the fuel map (your spark timing and that stuff is fine as its running on all four). If all else fails, faulty ecu?

[Jonny Rochester]

Since you have the factory computer and loom an everything, it maybe a good idea to also get the diagnostic engine light to also work. That way you could check for codes and be able to look up what the problem is. Your sort of in the dark without it.

???

[Mr Fujiwara]

well Jonny Rochester its funny you should say that, i just remembered i didnt tell you guys id done diag, and it said "vacuum" intake vacuum somthing...so what Nikkojoe sounds most likely, i will test the wires on the weekend, ive got work tomorrow till friday i'll let you know how it goes.

is there a rev limit on limp mode? or is the engine just reluctant to rev, and makes no power so you wouldn't ever rev it...

thanks guys, i was fearing i wouldn't get any feedback on this.

[Nikkojoe]

yeah, with my tacho working it rev'ed to 4000rpm (loads of torque then died in the arse at WOT above 4000). What was strange was that it would rev more if you let your foot off the accelerator slightly when above 4000rpm.

Oh and i melted my brand new cat heaps and used 1/2 a tank in 30km :D

[parrot]

I would be putting the right dizzy cap on for a start.

Out of interest, what injectors does it have?

[Mr Fujiwara]

well ive been trying to source the right dizzy cap for some time, someone said the Aw11 cap goes on, i ordered one, and it went on, but the bolt hole didnt line up, but, since they must use the same casting for the one i need (which i just cannot seem to find anywhere) i just drilled a holl where there was a circular mark already...and then it went on perfectly, and the car runs perfectly.

but yes, i noticed the car really does run like shit unless you back off on the throttle, its so weird.

injectors would be stock, i replaced the seals and sht in them when i got it (the engine), i have a VL Turbo fuel pump, but i fail to see how a bit more pressure and volume is going to make my car do what its doing.

[parrot]

Presumably you have a stock fuel pressure regulator so extra fuel will go back to the tank via the return you presumably have. A rising rate FPR wouldn't cause it either. Are you sure the injectors are stock? Colour / part number?

Not having a go but I would really make sure the cap is the right one.

[Jonny Rochester]

Higher fuel pressure will make it run rich. You want standard fuel pressure with a standard motor and injectors and ECU. From memory this should be about 35-40psi. The pressure should be limited by the stock pressure regulator on the fuel rail. You could check fuel pressure at the rail with a gauge if you like, if you have a gauge.

Have you tied getting the right dizzy cap from Toyota? It probably costs too much, but I'm sure you could get one.


Maybe you could clear the codes, (disconnect battery), and start again. Drive it and see if it still has codes. If you get a code for the MAP sensor for example, then either the sensor or the wires are at fault, and nothing else.

I hope this helps.

[parrot]

Of note, you can get RWD 4AGE dizzy caps on UK ebay for like GBP 3.00 plus post. Look in stores.

I run a malpassi rising rate FPR on mine with standard grey injectors without drama

[Nikkojoe]

Ive mentioned in another thread before, Bosch list a rwd dizzy cap (pn. GD687) as an ae82 item. I bought 2 a year ago and took both back as they only would fit a rwd jdm.

I don't think fuel pressure is the problem in this case.

[slydar]

wrong injectors. as others have said.

also if the stock pressure reg gets a small dent in it from being bumped in or out (or going into) the car, you fuel pressure will increase.

you will have a hard time finding the right cap, the EBAY uk suggestion is a good one i hadnt heard of. you can't source them from toyota anymore the the ae86 is discontinued apparently.

if your fault code says what its saying, then you may have a damaged loom. you could run the wires externally (to the loom) from the map sensor to the computer, to diagnose.

is there any difference in the engines when you have it plugged in or unplugged?

also check your cold start injector.. maybe its broken and constantly on for some reason? you can just disconnect the fuel line safely, the CS injector does nothing really. make sure to block the feed from the fuel rail.

also your plugs are really wet/fouled? just to make sure it definitely fuel we're chasing, no spark.

[Mr Fujiwara]

<div class='quotetop'>QUOTE (slydar @ May 20 2008, 04:21 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=533940)</div>
is there any difference in the engines when you have it plugged in or unplugged?[/b]


yes, the engine stalls with the map unplugged...so I'm not sure, i will check out the fuel reg and test the fuel pressure, as when we clamped off the fuel line, it evened out the revving considerably!

[Mr Fujiwara]

just for the record, it wasnt me who clamped the fuel line, nor did i give permission for it to be done, i knew someone at ultra tune and took the car there, and they TOLD me the car revv'd much more normally with the restriction on the line......so i can't 100% confirm this anyway...

and the Cold Start injector works fine, havnt checked the reg and stuff yet thou.

[Nikkojoe]

Have you made sure the main loom earth is bolted down on the intake manifold? Make sure every sensor is earthed (including map sensor etc), otherwise also try another ecu.

[Mr Fujiwara]

I've checked almost everything you guys have suggested, and i don't have the time to be stuffing aroudn with my car anymore, i need to know of somewhere who can fix it (I'm in melbourne by the way), ive even got to the point now i will pay a ridiculous amount for it to be fixed, i need this car running, as i need to take my 2nd car off the road.....as its VERY unroadworthy...

if you want to see HOW unroadworthly, just look here.... http://www.ae86drivingclub.com.au/board/in...showtopic=27005 (http://www.ae86drivingclub.com.au/board/index.php?showtopic=27005)

i was almost done for this last weekend, so i need my car working immediately!

ive been really considered going twin carbs lately, but it seems like such a waste, as i have a complete engine which is almost running normally...

cheers guys.

[AR_AE86]

have you tried the coolant temp sensor, this controls the turning on & off of the cold start injector & in some engines the duration of the injectors untill the engine heats up. if its not working right this will over fuel the engine even when is warmed up, try unpluging it while the cars running. the other thing it could be is a leaking cold start injector, warm the car up & then disconnect or block the fuel line to it.

good luck

[Nikkojoe]

<div class='quotetop'>QUOTE (ghecho @ May 23 2008, 08:10 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=535857)</div>
have you tried the coolant temp sensor, this controls the turning on & off of the cold start injector & in some engines the duration of the injectors untill the engine heats up. if its not working right this will over fuel the engine even when is warmed up, try unpluging it while the cars running. the other thing it could be is a leaking cold start injector, warm the car up & then disconnect or block the fuel line to it.

good luck[/b]


I don't think its that. Ive messed around with those sensors before and they don't make the car run in limp mode. The ecu is physically overiding the fuel maps in this case as it sees there is a serious problem.

[biggo]

the idle up circuit barley uses any sensors, so maybe theres a problem bewteeen them?