GreenBlood55

iTrader: (1)

I have been looking around the internet and have seen people with this same problem, but I swear every thread ends without the original poster explaining what the fix was.

Here is my issue. 94 z28 m6, cai, longtubes,borla, 8.5mm taylor wires,new accel 26lb injectors, new msd cap n rotor, new ecm

The car is hard to start, it turns a bunch of times then barely starts. I need to keep tapping the gas peddle to keep it from stalling. I have gotten it to stay running on its own without tapping the peddle, but the rpms bounce from about 400 to 550 rpms, and the car shakes like crazy. It will hold on to idle for a minute or 2 then stall out. It is also producing a strong gas smelling smokey exhaust.

I just bought this car, knowing id had issues and hoping it was a minor fix. Does any of what im explaining make anyone think of something obvious? I can turn a wrench, and replace parts, but im horrible at diagnosing.

I really dont want to have this thing hauled to the dealer for them to charge me $400 to tell me a spark plug is bad.

Any ideas?

GreenBlood55

iTrader: (1)

Update..

I just spent about an hour outside messing with it. I changed the cyl.3 plug as its the easiest to get to. It was black, and smelled like gas.

I checked all the connections to make sure everything was on tight, then started it up. It took a few tries but it did start, and again i needed to tap the gas peddle to keep it running.

After a few minutes i stopped tapping the gas and to my surprise it held a almost steady idle at about 800rpm. It was still bouncing but maybe <50rpm. I also noticed that the battery indicator was almost in the red, and the brake light where dimming with the idle bounce. I rev'd it to about 1200 rpm and the battery indicator raised and leveled off, and the roughness almost went away.

As soon as i took my foot off the peddle, it would go back to about 800rpm and continue to do what it was doing previously.

I attempted to raised the rpm up to about 2500 and the entire way up, the car sounded like a card in a bicycles spokes, i let off the gas at about 2500rpm and as the rpm fall i get a backfire.

Things i observed as i was doing this.
1. No smoke out the exhaust
2. Still have a strong fuel odor
3. The temp. gauge in the car doesnt appear to be working
4. The alternator is newish and is screaching
5. The cai sounds like a friggin supercharger whine, but does not make a peep until the car runs for about 2 minutes

GreenBlood55

iTrader: (1)

For shiggles, I went out and unplugged the mass air sensor, and started the car. it started right up, idled at 1k rpm, still idled rough, and did the same thing when attempting to rev engine. sounded like crap and backfired on the down swing. also threw the SES light

GreenBlood55

iTrader: (1)

anyone?.. anyone?? bueller......

96TransAmboosted

iTrader: (8)

Have you checked spark? How hot was the spark?
Fuel pressure?
Running rough could be anything ignition related ie plugs wires cap rotor.

The MAF could be the issue as well. Any thing we suggest will only point you in a direction but diagnosis will be need of each system to make sure there working correctly.

BOBS99SS

iTrader: (2)

damn opti strikes again lol, for real though ^ this is good info,have you had the car scanned

GreenBlood55

iTrader: (1)

Havent had the car scanned yet... HOWEVER... Tonight I decided to start the car in the darkness to see if there where any fireworks under the hood. I found a very obvious arc on what looks like the far back plug wire on the passenger side, up by the plug boot. It was a rapid constant flashing. Could this 1 single arcing plug wire be the whole problem?!?!? I cant change it until tomorrow, now im praying its just that.

I mean, could 1 measly arcing wire cause the problems im having???

jaycenk

iTrader: (1)

No it will add to the overall problem but if your plugs on other cylinders are fouled then you have something else going on as well. You have to do the basics with these cars. Fuel injection cars are really no more complicated then carbed cars. They just require a couple of extra tools and the knowledge on how to use the tools to help you find the problem. A scanner is a must have. You don't need a high dollar scanner a stop by a parts store can get you the codes the pcm has. If you can’t make it to the parts store, there are scanners out there for around or under 50 bucks that will give you engine codes that you can post up on this site and someone can tell you what it means. Also a fuel pressure tester is another must when dealing with fuel injection. Everything in the PCM programming relies on the fuel pressure being at the right pressure all the time. if it's not the pcm on these cars really does not know how to react. then there are the basics like checking plugs and wires. If your plugs are fouled then it's time for a new set of plugs. if the wires are old or burnt to hell you might want to just buy a new set and TAKE THE TIME to make sure they don't get burned again. Once you have a good set of plugs and wires on it and verify the fuel pressure is ok then it's time to diagnose what is causing them to foul. Some times codes are thrown that can lead you down the right path. Last but not least, you need to tell us about the car. We suck at mind reading lol. What year, What transmission, is it all stock, do you have any boltons? any engine work done? how many miles, was the opti replaced ever? Help us help you.

GreenBlood55

iTrader: (1)

jay, i posted most of that information already. the car has a newer msd opti.


I checked last night and saw the fireworks on the #8 cylinder. Today I went to change the #8 plug and wire and the plug itself was cracked bad around the ceramic. I noticed a break in the wire close to the boot as well.

i changed them out and started the car. it fired right up and held idle right at 1k rpm. attempted to rev and it still sounded like a baseball card in a bikes spokes.. I thought maybe i didnt put the wire on all the way. The car only ran for like a minute, but when I went to check the wire, the header on #8 burned my hand.

So, I felt the other headers.. and this was the result..

1 hot
2 cold
3 hot
4 cold
5 cold
6 cold
7 cold
8 hot

I changed the plug on #3 yesterday because it was easy to access and it was fouled pretty good.

any ideas on whats goin on here? the car has a bunch of mismatch plugs that are rusted around the bolts. 3 and 8 where completely different brands/styles and i can see that 7 is def. different than the 2 i already pulled.

ZFreie

Have you tried replacing all plugs and wires if they are all mismatched and fouled...?

GreenBlood55

iTrader: (1)

Not yet, im in the process. Im hoping to finish changing them all out tomorrow. I do find it interesting that the only headers that where hot, where on the 2 cylinders that i just put new plugs in, and the #1 cylinder.

GreenBlood55

iTrader: (1)

the other thing, even if the plugs are older, and mismatched, what are the odds of every one of them being fouled?

ZFreie

Well Id wager you getting a misfire on every cylinder that the corresponding header wasnt hot.

You said your self one plug was broken why would you think the rest are in any better shape? Id replace every plug and wire with NEW and see what happens.

My DD civic would hardly idle and run, I replaced the wires and plug and rotor cap, and it ran like brand new.


Didn't even see this, this proves even more that the plugs are your issue, you said you self the ones that were getting hot where the ones you replaced. replace all with new and see what happens.

GreenBlood55

iTrader: (1)

is it normal for firing cylinders to make the headers get really hot within like a minute of running?

jaycenk

iTrader: (1)

Sorry man I totally missed that line in the original post.
As for the headers getting hot, what is hot? like glowing red hot? or burn you hot? Burn you hot is normal. They should all be at that temp after a min of running. They may not be hot enough to leave skin on them but hot enough to burn the **** out of you.

GreenBlood55

iTrader: (1)

Not glowing. But enough to get my attention when the back of my hand hit one of them. Burned, but didnt melt skin off. How in the hell did the car even start if 7 of 8 cylinders had fouled plugs?? smh..

96TransAmboosted

iTrader: (8)

Only way to tell a cylinder temp is not by using your hand but by using a thermometer to read each cylinder one at a time. Of the temp readings are way off from each other then you know there is an issue

ZFreie

Id wager that some being cold to the touch and some burn you would indicate a huge difference in temps lol

GreenBlood55

iTrader: (1)

uugghhh changed the number 2 plug, started it up, and the tube on that cylinder is still cold.... smdh...

GreenBlood55

iTrader: (1)

So I caved and took it to a mechanic to check out. Mechanic says 1.The computer in the car is for an automatic and 2. The computer is bad 3. The computer is only firing 3 cylinders.

The kid I got the car from did tell there was a computer issue, but not that it was bad. The mechanic is telling me i need to replace the computer before he can test anything else ie: opti.

Does anyone know where i can get a CHEAP 94 lt1/t56 computer??? I need one ASAP.