I have done a search, I will be checking the pickup coil this weekend. That
said I figured it wouldnt hurt to see what the forum thinks.

The Car :

1986 Camaro IROCZ28 350 block with 305 top end and 350 injectors. Other
than that its pretty much stock. So many things have been replaced on a
trek to fix it : TPS, IAC, MAF .. etc. The biggest change came from doing
a simple cleaning to the TB, resetting the idle, and adjusting the TPS. This
I learned from the Alt.Camaro newsgroup a number of years ago. Prior to
that the car would throw a MAF code each time you drove it. Somewhere
along the line the plug was knocked out and the idle was adjusted. I had
a leaking injector and replaced them all with the 350 sizing/flow. Heads
are rebuilt, compression is the best I have seen any engine in consistency
between each, highest and lowest, etc. Fuel pressure is 38 PSI at idle to
over 40 psi when you stab it.

The Symptoms :

Seems to take too long to start. At slow speeds it bucks like a bronco. It
also seems to upshift way too soon. Its hard to tell if its a trans issue or
an engine issue. It chugs also under light pedal and low speeds. Sometimes
its so bad it can give you a neck pain, its like someone grabbing you at the
shoulders and shaking you from behind.

Tom

 

Oh Man my Iroc did that before it caught on fire!

My fire started in the coil area so maybe its spark related.


John

 

No input guys? Really? If you drive it like you stole it it runs great. Its the low speed
lugging where it acts up. I have read that the early cars lock the converter too soon.
Its hard to tell what is causing it. Sometimes I think trans. Its an odd ball trans
too, the '86 trans took a dump, so we got one from a 1991 Camaro, but it turned
out to be a 1984 case, with a 1991 front pump/input shaft : Frankentrans.

Tom

 

my 91 tbi formula was like that. would chug it even at 25. felt like lock up was always on. was a rebuilt tranny tho and just kinda got used to it. shifted so crisp and clean.....

 

Connect a scanner and find out what the TCC is doing as well as Integrator and BLM.

 

My wifes truck did something like that and it turned out to be the egr valve. When she would go from reverse to forward it would die and it would seem sick at times. It never bucked.

 

A stuck open EGR can cause very poor engine performance. Always a good thing to check.

 

Wouldnt a EGR valve cause backfiring or other issues when floored? With the
IROC, you stab it and it GOES, its the low speed circuit thats weirded. I have
a scanner, I will dig it out and look. It will show when the computer makes a
command to lock the TC? I have an aftermarket chip, I wonder if that will do
a delay on the convertor lock? I got it from someone who pulled their 305 to
install a 383, and the chip needed replacement.

Tom

 

i had the same exact problem, but as long as i was getting on it or keeping rpms high i was good.

 

What was your solution? Live with it?

Tom

 

i took it as a sign that its time for an lsx swap. its been parked for about 6 months now. i got it all torn apart and taking it next week to pull engine and tranny. then prepping the body for shaving and paint.

 

I considered swapping in the LT1 from my wifes wrecked '95 Camaro Z28 a
few years ago, but we are not keeping the car.

Tom

 

EGR stuck open will not cause backfiring. It's inert gas from the exhaust being injected into the intake air and will cause loss of throttle response and rough idle. Its affects will diminish with higher throttle openings and at higher RPMs as more fresh air and fuel is added. ECM data should show TCC on/off. A TCC stuck on will cause the engine to stall rather harshly when stopping in gear. This is a common problem with early style GM TCC solenoids.

 

how can i stop the inert gas from doing that? im a noob.

 

You can remove the EGR. There are differing opinions on this. I am of the belief that it is better not to remove the EGR on an otherwise stock engine, especially with stock fuel map. These cars were designed to run lean for emmisions and, believe it or not, fuel effiency. The inert gas injected by the EGR keeps combustion temps down in these lean burn engines. Without the EGR, I've seen valve damage after extended periods of highway driving.

When operating normally, the EGR will only open under part throttle cruise conditions where it doesn't affect performance. It closes at full throttle and closed throttle. Only when either the valve or the control solenoid fails, will the valve open abnormally. Also, carbon chunks can become lodged in the valve and cause it to stick open.

 

Maybe the hall sensor is giving up on you. I remember my dad changing that pickup/sensor to get rid of an rpm govenor on a truck years ago, after he changed it out the truck felt like it had a new engine.

I finally got a chance to pull my harnesses apart and the damage from the fire is not as bad as I thought.

Good luck let us know what you find or what fixes the problem.

 

The HEI does not use a hall effect sensor. It does use a magnetic pick up coil and permanent magnet pole peice and timing core. This system is subject to failure with age. I thought someone already mentioned carefully checking the distributor for rust or damage and measuring resistance of the pick up coil, should be 800-1000 ohms. Take the ignition control module in for testing.

 

Is there a way to test the ICM without taking it somewhere?

All the places around here claim they can't do it anymore.

 

this is an egr problem and pickup could, I just had this issue. try seafoaming the crap out of your motor or apply vacuum to the egr at idle.

 

Sorry about that I'm an aircraft electronics tech I thought is was a hall, but at least you knew what I was talking about.

Thanks Doc

 

Yes, and GM did use a hall effect switch in the 4cyl. distributor. I guess the larger size of their HE sensor made packaging an issue on the V6 and V8. My ACCEL Billettech uses a simple magnetic pick up with an iron reluctor wheel which is a much less troublesome design.

 

She ended up having the IROC down in LA the entire weekend, and since I'm
alone this weekend I will have plenty of time to put the scanner on it. I'm
leaning toward the lock up soleniod, but maybe thats wishful thinking.

Tom

 

Watch integrator and BLM for going lean or rich. I would have you watch manifold vacuum if you can connect a gauge and set it up where you can see it.

 

up dates?

 

Not yet, sorry I have to wait for the weekend - tomorrow!

Tom

 

I went out armed with the scanner, a print of this thread, pen, and vacuum
gauge - the battery was deader then dead. I went and bought a new one
and it fired up and ran great. Idle seemed high though. Driving around the
chugging, bucking and surging was 90% better. I only got it to chugg one
time during the drive and it was like 2 or 3 and gone.

Vacuum : 20 inch decell/idle and 5 inch accel.
BLM : 130-135
TCC : couldnt find a command on scanner.
Integrator : 130-132

Converter feels like its locking at 40 mph, though it does seem to upshift a
bit too soon, light pedal it cruises up through the gears.

With the new battery it seemed all but cured. I have read this can throw
off the system, but I had no idea it could be that drastic.

Tom

 

Cool,

Well check all your grounds and connections, make sure they all clean and in good condition.

Get some QD plug cleaner and some dielectric grease, take your battery loose and go nuts on every connector you can find.

Make sure the wire that goes to your alternator is in good shape, and make sure that you have a sizable ground that not only goes to the block but also hits the body somewhere.

On aircraft once we get a good ground/bond we paint over the connector and bolt with fuel tank sealant but on a car thats is not necessary, but they do make battery/electrical terminal anti corrosive spray that can also be used on your grounds.

 

Have you replaced the fuel filter??? or checked out a new fuel pump???

 

I checked the fuel pressure and its correct for this car. I changed the
fuel filter recently. When I drove it with the new battery it seemed like
a different car. I did find out however, that the battery was dead from
the light in the trunk having been left on (it killed the new battery). So
I was going to return the new battery if the old one I have works. I may
have to keep the new battery, chances are they wont take it back.

Tom