I've done just about everything possible to make my Camaro run right, but it will still just barely chirp the tires when I stomp on it. It seems to run better above 2800 RPM or so, and feels weak below there even though a TPI motor should be plenty strong at lower speeds. I've replaced any questionable control system parts, new injectors, completely new ignition except the distributor housing and gear, new IAC, EGR, CTS, O2 sensor, TPS, new TPI and intake base gaskets, you name it, I've done it. The damn thing still dies in reverse sometimes and idles low in gear when fully warmed. The engine also sounds like it really struggles when I put it in reverse. Compression is 185-192psi on all eight cylinders, valve lash is set properly, fuel pressure is good.

The engine easily revs in neutral, but it just seems weak for 350lb-ft. of torque in drive. No plugged cats either, they are gone.

I'm thinking this has to be some problem with the torque converter (stock), and the tranny fluid was dark with a nasty gear-oil-like smell when I got it with 33K on it. However, it shifts fine. Go figure. No vacuum leaks around the engine, but I suppose it could be something flakey like the power brake booster.

If anyone has any insight on this problem I would be very grateful. Thank you for your time.

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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley AFPR, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Ruger P95DC, hot wife, new oil filter, thick rubber floormats, no cats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

Jethro,

You mentioned no vacuum leaks but failed to include the vacuum at idle. If you have a guage, the stock cam should provide about 17-19" at warm idle.

The brake booster is a potential vacuum leak - I chased one around for a while myself. The PCV is another potential problem, but both of those can be eliminated easily by simply plugging their respective hoses. You can run without PCV for a few days without creating and significant sludge buildup, and the loss of brake assist doesn't mean you can't drive the car, but drive carefully and realize that there is a LOT more pedal required to stop the car.

The first thing I was thinking was low compression, but as I read on through your post you killed that theory. Your compresion numbers look really good.

Sludge in the TC is another possibility, since thickened oil will lower the stall speed of the converter.

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Later,
Vader
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"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

 

Thanks Vader. The vacuum last time I checked was around 19in.Hg. at idle. I've changed the tranny fluid twice, along with siphoning some out of the dipstick tube and replacing 5 or 6 times, so it's pretty clean in there. PCV system and hoses are new, although I haven't checked the brake booster yet. I'm still thinking the TC since it doesn't seem to want the engine to rev at all before it takes off. It's like the stall speed is set just off idle. The TCC seems functional, if I get up to about 60mph and tap the brakes while I hold the gas the TCC unlocks properly, so that killed my theory about it being locked all the time. It just feels like the engine is fighting something more than necessary when accelerating until higher RPM. Maybe I'm just expecting more from the car than it is, but something has never "felt right" about it. Thanks for the input.

 

Jethro,

First, let me explain that I'm not try to be condescending. I know that you have a very good understanding of the systems at work, but I wanted to cover the list of possible causes, just so something isn't overlooked (and for the archives):

Lack of Power

1. Incorrect timing, either valve or ignition;

2. Faulty ignition - distributor and rotor contamination, weak coil, HEI module, failing reluctor and pickup coil, failing plug and coil wires, glazed plugs, or incorrect plug gaps (usually too wide);

3. Contaminated or low-volatility fuel;

4. Fuel delivery problem - filters clogged, faulty pump, low float in carburetor or clogging injectors, sticking regulator, line restrictions;

5. Lack of compression - Failed head gasket, damaged valves, incorrect valve lash, damaged head or piston, worn rings;

6. Plugged or restricted exhaust - collapsed pipe or muffler, damaged tailpipe and tips, clogged catalytic converter;

7. Restricted air cleaner;

8. Weak valve springs (allowing float);

9. Excessive driveline friction - low tire pressure, tire interference, failing wheel/differential bearings, incorrect pinion angle, dragging brakes, excessive vehicle loading;

10. Slipping transmission - broken pressure plate, worn clutches or bands, torque converter internal loss or damaged turbines, damaged output shaft spline.

These are the routine causes of lost performance. Since you have apparently never had the kind of performance you've expected, there may be other things involved, but if you can clear this checklist, it should eliminate a lot of the possible variables. You've already coverd a lot of then in the information you've provided. Compression and vacuum look good, and the ignition is apparently O.K.

If the car has NEVER run as you expected, it might be worth dropping the ECM from the right side footwell and seeing what PROM number and revision you have - just in case someone has been there before.

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Later,
Vader
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"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

 

Thanks, man! I know you're not being condescending, and it's always helpful to have a list like that because thanks to my Pabst Blue Ribbon brain I tend to forget or overlook things. Good call on the ECM and PROM, I'll have to pull it and check it out. Been meaning to do that for some time but I forgot . Aside from that, I need to do more looking into #9 and #10. Again, thanks for the input.