Heres the symptoms. Its a 305 TPI

-When i rev it in park it has a lot of hesitation.

-Under normal accelaration the car has a bad miss to it. Almost like a plug wire fell off. (but ive gone over them all)

-It has an irradic idle

-It seem to surge up and down when im on the highway

Right now the only thing i can think of is the injectors. I still have the original ones at 92,000 miles. Any other ideas?

 

87,

Before you remove the injectors, try a few standard diagnostic steps first.

Check the spark plugs themselves for wear, fouling, and incorrect gaps. Check the resistance of each ignition wire and inspect them for cuts, cracks, and burns. Clean or replace the distributor cap and rotor.

While you're in there, take a look at the pickup coil and reluctor. The pickup coil should measure between 500-1,500 ohms, and infinite resistance (no reading) to ground. The reluctor should be clean and have no signs of cracks or damage.

Look over the low-voltage wiring of the distributor and coil.

Make sure you have some compression on all cylinders. A good time to check that is when the plugs are all out for inspection.

Try monitoring the fuel rail pressure. A clogged fuel filter, failing pump, or failing pressure regulator can cause those symptoms as well. If the presure is 37PSIG -/+ 3PSIG at idle, you should be O.K. The pressure should increase to about 44PSIG when the vacuum line is removed from the pressure regulator.

If the pressure is O.K., try disconnecting the injectors one at a time with the engine idling. If you have an injector that is not functioning, you will notice little or no difference in idle quality and speed when you disconnect that injector. Reconnect the injector and move on to the next one. If you find a bad one, remove them all for cleaning and flow-matching. I've had very good experiences with Cruzin' Performance. Check their site for prices and details.

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Later,
Vader
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"Click - Click - BOOM!"
Adobe Acrobat Reader

[This message has been edited by Vader (edited September 07, 2001).]

 

Thanks for the help. I know my fuel pressure is ok. Ive got AFPR and the pressure reading is perfect, its not fluctuating at all. I guess ill pop off the cap and check the rotor next.

 

you getting any codes?
might be the maf or o2 sensor.

 

I'll check the O2 sensor....

 

Well the cap was toast so i replaced that and the rotor. It seemed to fix it, but later tonight all the symptoms came back. Im not throwing any codes, the maf is fine, and its a brand new 02 sensor. Im thinking maybe a clogged up fuel filter. Im going to try that next.

 

Don't know if this is way off base...when my 92 was brand new it had the same problem you are describing...hesitation, rough idle, never threw any codes. After about 15 trips to different dealers, it was finally traced to a damaged circuit in the computer. They replaced it under warranty and it's never had another prob since... just my experience

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1992 25th Anniversary z28 Convertible

 

could a really clogged cat cause that?

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

 

The cat is also brand new. So thats not it.

 

i'm 99.9% sure it's injectors. have them flow tested and i bet money 1 maybe 2 are bad.