Car: 88 Camaro Iroc Z
Mods:
Edelbrock intake
SLP runners
1 5/8 headers
No cat or air pump
AFPR
3.41 gears originally 2.77
Problems:
It starts to lose power when driving on the highway
(sometimes after two hours of driving, and others after
20 minutes)
Then if I stop for a minute, the problem goes away, and
comes back after a while of driving.
the car gives me the error code 42 and 45 also, and it
smells a lot like gas when the car is acting like this.
It backfires really gad when I accelerate and let go the gas.

Things I have replaced:
Ignition coil, cap and rotor
Ignition module
Electronic Spark control module

The error code #42 refers to
Fault at electronic spark timing circuit or
Fault at direct ignition system or
Fault at fuel cutoff relay circuit
My fuel pressure remains the same when the problem shows, so I think that I can eliminate the third one. Right?

If you know anything about what can solve this problem or what do I have to replace next or what to check, please let me know.

One more thing that could be a clue, is that this problem first happened one time that I went to test how well the new tranny shifted: I floored it on first gear and missed to shift to second on time and the engine revved past the red line, I think it went all the way up to 7000 revs or something like that. So the same problem showed up and it went away the next morning without me doing anithing to the car. But the problem came back all of the sudden a month later when cruising on the highway at like 65 or 70 MI/h. And it happends more often now, but it does not stay.

I really think that this hods the answer to this problem but, I just can't see the connection . I hope any of you can.
Thanks a lot

 

not sure where u got ur code meanings from,but i get mine from here:

http://www.angelfire.com/wa3/ivhorsepower/diag.html

code 45 is the O2 sensor sensing a rich exhaust mixture
code 42 electronic spark circut grounded

not sure which is right,but their something to look into now,hope this helps

 

A bad timing chain or bad valvesprings could also cause a similar problem, especially considering your overreving debacle. Keep in mind that those trouble codes can't replace thorough diagnoisis of the problem. A lot of times I've seen problems with EFI car that had nothing to do with the trouble codes thrown. The ECM sensed that something wasn't right, and threw the code that seemed the most appropriate. You're getting a code related to a symptom though, not the cause. Keep this in mind.

If the mechanical stuff checks out then I would suspect wiring problems. Inspect the wiring to the components in question thoroughly.

 

Quote:

A bad timing chain or bad valvesprings could also cause a similar problem, especially considering your overreving debacle

The same thing I thougt when it happened for the first time, but the fact that the problem went away by itself the next morning and I was not able to reproduce it, had me wondering.

Can a mechanical problem, like a bad spring or a bad timing chain, cause an intermitent problem, I mean one day I can drive two or three hours, and very smoth, with lots of power, going uphills and everithing and suddenly, it looses the power even to keep 50 mph?

Quote:

not sure where u got ur code meanings from,but i get mine from here:

I got them from thirdgen.org, from the FAQ section, I'm hopping this is right.

Thanks a lot for the input guys, I'm trying to determine where to go next and to find out if this is a mechanical or electrical problem

 

Problems like that are most likely timing chain related as opposed to valvespring. It could definitley cause a problem like that. When it's cold it takes up some of the slack, so the problem isn't immediately noticeable. Also, if you're driving at highway speeds under constant load it may no start to experience a problem until you let up off the gas and the slack becomes a factor again. The problem is most definitely timing related.

Another possible culprit is the shear pin in the distributor for the gear. I've seen similar problems caused by this item partially failing too, though small block Chevys don't have this problem as often as other motors.

It's still worth checking out the valvesprings. I don't think they are causing your problem, but they could be contributing to overall lowered performance if they are damaged. You ought to look for burned rocker pivot ***** too, while you have the covers off.

 

Hmmmm, from what I've read so far in this post the problem could still be either mechanical or electrical. The one thing that caught my attention though is the trouble code referring to the spark circuit going to ground. A mechanical problem is usually pretty consistent. If your spark timing all of a sudden changes, such as being retarded or losing voltage, this could definitely cause a big loss in power and acceleration. I think I would rule out any electrical problems first. On the mechanical side, you can always run a compression test and a leakdown test to find out if you damaged any of your valve springs.

 

Quote:

The one thing that caught my attention though is the trouble code referring to the spark circuit going to ground. A mechanical problem is usually pretty consistent.

Excuse me if the question sounds kind of dum, but what it means when you say that the spark circuit is going to ground?

And yes, you are right, in most of the cases a mechanical problem is pretty persistent, and in my case, this car, one morning, I can start it, and drive it all day, I mean to the store, and to the car wash, and the car being very strong, I mean, If I floor it, it will spin the tires very easy when changing on to second gear. What I'm trying to explain here, is that when the car is working good, it runs very, very smooth, and with all the power that the motor can give, and when the problem appears, it is very hard to pick up even 20 mph from a stop.
For me it seems like the symptoms of an electrical problem, but I'm not completely sure. I need more opinions please.

What it really has me frustrated, is that the problem does not stay, so, I can't track it, cause when I get home, the car is running like a champ.

Your opinions and, testimonies from your experiences are very helpful guys.

 

Mechanical problems aren't always consistent, and I've had several trouble codes in several different vehciles that proved to be mechanically related. All of the codes were intermitten. Don't rule mechanical problems out yet.

 

You should check your EGR iis operating correctly. Your symtoms sound exactly what happens with a bad EGR.

 

Hmmn, the codes could be related..I'll toss this out...

The code 42 cuold be from a faulty connection in the EST circuit...code 42 will set when you disconnect the EST bypass line to set your basetiming....

So say the connection (or line somehwhere) disconnects...your timing reverts to base timing...i/e 6*BTDC or so...when this occurs the A/F mixture won;t fully ignite, and unburnt fuel will exit he cylinders...could be why the code 45 is set....plus the immedieate loss of power due to too little timing advance.

If it were me, I'd chase the code 42 first and fix it, see if the problem goes away.

A scan tool would be invaluable to verify this.

 

Not a bad idea. Do the old wiggle test while holding continuity probes through that circuit.

 

This problem sounds familiar.

My car did about the same thing. Would run fine around town, and great for a while on the freeway. But, after about two hours of steady state cruise, service engine light would come on, and power would drop off dramatically. Could hardly pull away from a stop light...... Mine turned out to be the pickup coil in the distributor. It would get hot, expand, and stop working correctly, I would lose 4 cylinders. (a v8 just does not run well that way....)
I ended up swapping in another distributor, and my problem went away. Completely.

I was also getting the same codes you are.......

Pickup coils are cheap, but fun to change. Took me about an hour and a half to pull and disassemble the dist, and get the car running again. (customer car, similar problem) The Dist swap on my car took about 20 minutes........

 

Thanks a lot for all your responses.
I'll check the EST bypass connection.
It is a PITA to look for the cause to this problem because most of the time the car is running fine, I have to drive it and wait for the problem to show up to start looking for the cause.
I'll let you know if I find something new.
And please, keep the suggestions coming.

 

Quote:

My car did about the same thing. I ended up swapping in another distributor, and my problem went away. Completely.

Did you find out exactly what was wrong with your distributor?
I mean, what part was bad inside of it.
Did you replace it with a stock one or a high performance replacement, if you did the second, can you tell me what part # you used please?
Thanks

 

Yesss!!!! I think that I solved the problem.
I found out that the resistance in the pick up coil was like 280 ohms, a lot lower than what it was suposed to be.
I tried replacing the pickup coil, but when I took the distributor apart, the magneto on the mainshaft lost a piece, it looked very bad and rusty, so I decided to buy an MSD distributor, I installed it and have had no problems ever since.

You were right ploegi.

Thanks a lot to all for your help.