3.4 problems have me stumped

[White93z34]

ok, so friday i started work on the euro 3.4. i put a battery in it and drove it up to the shop. when i did it had almost ZERO power it felt so castrated and it was missing.

i got in the shop and pulled the plenum and lower intake, i figgured that at least 2 of the injectors were not pulseing correctly, so i replaced the complete fuel rail and injectors. i put it back together, and started it up, but the first few tries it wouden't start and it seemed to backfire through the intake then it started and didn't miss anymore but it was still running really rough. it will idle at 1000 and i can rev it to 3000 and it will do so, but feel really choppy all the way there. and now its pulling a constant code 34. i tried swaping the PCM, but that made no difference. the spark plug wires apear to be brand new, the last owner claimed he bought new coil packs and ICM as well, but i have yet to check that to verify. and after about a minute it will stumbe and stall.

when i pulled it apart i noticed that it looked like the vaccum line to the fuel pressure regulator was unpluged, and that vaccum line that goes over the pushrod blockoff plate was broken so i replaced that. i double checked all the vaccum lines, they are good.

i'm so totally lost here..

[DreX]

RE: 3.4 problems have me stumped

That sounds like timming or electrical wire failure. The most challenging fixes of my swap was the electrical trolls. Even today I have the CTS wired over the plenum due a false conctact somewhere in the harness. Works good now tho.

This will help you with the codes. http://www.w-body.com/ecm-codes.html


Dre

[DreX]

RE: 3.4 problems have me stumped

Heheh, I hit it. This is from the previous link.



CODE 42

Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system. During cranking, the timing is controlled by the ignition module and the ECM grounds the EST line. It expects to see no activity on this line at this time. When the ECM enters EST mode, it applies +5 volts to the BYPASS line and expects to see voltage variations on the EST line.

Reasons for the ECM to set Code 42:

System in BYPASS mode (i.e. EST line supposedly grounded) but activity sensed on EST line
System in EST mode (i.e. BYPASS line driven with +5 volts) but no activity seen on the EST line
Possible causes include:
BYPASS line is open or grounded
EST line is open or grounded
Poor connections between ignition module and ECM
Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise
Faulty or incorrect ignition module
Faulty ECM


Now have fun. Hope Helped.

Dre

[White93z34]

RE: 3.4 problems have me stumped

whats code 42 have to do with this? all i'm getting is code 34.

as for the timeing, is there anyway to check it?

[dohcfiend]

RE: 3.4 problems have me stumped

troubleshooting the engine was a pain for me until i bought a scanner. best $180 bucks i spent and if your friends have gm cars u can charge them like 10 bucks to use it. if it is missing it most likely is an ignition fault since you have replaced the injectors. i have 6 coilpacks i am selling. 3 for 40 and 3 for 60. i have an extra ign module but i am iffy about selling it in case i need it.

if it is a wiring fault, break out the test meter and have fun.

[DreX]

Re: RE: 3.4 problems have me stumped

whats code 42 have to do with this? all i'm getting is code 34.

as for the timeing, is there anyway to check it?

Sorry about the wrong code. I guess was a bit sleepy. But anyway check the link for the code you need.

Dre

[White93z34]

RE: Re: RE: 3.4 problems have me stumped

i got the code and SES light to go away, the map wasen't fully plugged in.

but it still runs like garbage, no power, idles rough, accelerates rough, likes to stall.

[grandprixgtp_91]

RE: Re: RE: 3.4 problems have me stumped

has it alway run this bad? because if it used to run good then its not the timing.

Jake

[White93z34]

RE: Re: RE: 3.4 problems have me stumped

i bought it this way, and i'm trying to sort it out. my origional plan was to use it as a winter ride, but things changed and when / if i get it running it's sold

[White93z34]

RE: Re: RE: 3.4 problems have me stumped

update on the car, the day before yesterday it quit starting. it will crank and crank and sometimes catch and try to start but then it acts like it looses spark and keeps on cranking. also it will sometimes pop through the exhaust or backfire through the intake.

[93RegalGS]

RE: Re: RE: 3.4 problems have me stumped

I'd check the ICM, coils, and maybe even check the crank sensor.

[blk92z34getrag]

RE: Re: RE: 3.4 problems have me stumped

Try flooring the gas while you're cranking it over. This will cause the computer to use a different start up fueling method... or something... I dunno but it starts my car when it doesn't want to start.

[Juglenaut]

RE: Re: RE: 3.4 problems have me stumped

Replace fuel pump??? or are you just waiting to find other problems, Test fuel pressure.

[White93z34]

RE: Re: RE: 3.4 problems have me stumped

ok update! last night we changed the spark plugs and put some better gas in it, the old plugs looked prety new but reeked of fuel. i checked the spark plug wiring, noticed that a few were incorrect so i rewired them all. we had it running once and it would only stay running if it had lots of throtle applyed. it didn't sound good at all either. when i bought it the guy who sold it to me said it needed a cank sensor and that he replaced the coils and icm (however i haven't verified this) it does have brand new sparkplug wires. and we have spark. man alive this engine has got me stumped.

[blk92z34getrag]

RE: Re: RE: 3.4 problems have me stumped

Have you tried replacing the CPS?

The CPS went on my mom's car and you couldn't get that thing over 3000RPM it would act like it was hitting a rev limiter.