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]

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]

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]

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.