94 cav that surges... help!

[cujotom]

hi guys. i have a 94 cav 2.2. i experience a surge between 35-50 mph range only when you feather the petal. if you accelerate, no problem it responds. if you decelerate, no problem. only when you barely touch the petal. complete tune up, o2 sensor were installed. no check engine light. and performance nor gas mileage seems to suffer. it is just annoying, also tried and reset the ecm or is it pcm, no help. i also cant seem to be able to pull any codes by putting a piece of wire in teminals a+b in my obd module, can you do this with the 94? can anyone help? thanks

[Three_Fingers]

My guess is the throttle position sensor is worn out at the tip-in or part-throttle position.
All it is really is a potentiometer-kinda like a volume control-y'know how sometimes when the volume control wears out on an old radio? Sometimes in one position it'll be near silent, but if ya tap the knob or move it ever so slightly-it'll blare at you.
TPS will do the same thing only instead of blaring, it'll cause intermittent bursts of fuel from the injectors.
You can test both sides of the TPS with an ohmmeter. Look for radical jumps in resistance at or near the throttle position you describe.

Pulling the codes? Some '94 J-bodies had OBDI systems, but I think they started going to OBDII halfway thru the year. Some cars had OBDII systems with OBDII ALDL ports and some had OBDII systems with OBDI ports. I think by '95 they were all OBDII and you couldn't get the codes with a jumper anymore. Are you sure you're connecting the A+B terminals?
They're not always in the same configuration.

[cujotom]

thanks 3 fingers for your help. by the way i had installed a new tps. which didnt seem to solve the problem. that was the very first thing i did. i than went to the 02 sensor, changed that, no change. just recently i changed the air cleaner temp sensor, pulled the neg cable for 1/2 an hour. that seemed to solve the problem. a combination of sensors gone bad? i wish i knew. as i didnt have a digital meter to check them. it gets very expensive to start changing things all the time, not a smart thing to do. thats more than likely the reason why i am not a mechanic.....
( even though i like to think i am! ) lol...
as far as the proper pinning out . i will recheck as you said and try diffrent pin outs.i tried according to the hayes manual. ( top two pins, left side, marked term a+b, is there a possibility of screwing up anything if i pin out something wrong? again thanks for your help...

[CrzyTBear]

I was just wondering if you got the trouble codes off the computer I'm having the same problem .. Every where I go wants to charge me $70 to read them. Any help would be apreciated.

[Three_Fingers]

If yer really desparate-any good public library has the same manuals that repair shops use. The codes are in there-and the troubleshooting flow charts to solve the problems-copies of pages are cheap.
I find mine on the net-just type in "GM OBD1 or (2) trouble codes" and something always comes up that you can use.
IF you have a GM car made until somewheres around mid '94-it's OBD1 and you can pull the codes with a paperclip between the ALDL a=b terminals. Late 94 (some models-Cavys included) and up are OBD2 and you need a scanner. Disconnecting the batery won't clear all the codes either because it's got a non- volatile memory to save codes for the service tech with the scanner. I'll prolly have a chance Tuesday-I'll post the codes for early stuff here.

[cujotom]

no i was not able to pull the codes useing a jumper. i need the scanner. by the way the car was manufactured in feb, 1994. as far as the surgeing went, after all was said and done i found that my egr valve is shot. i just plugged up both sides egr side and vacumm side. the car runs great, no problems with gas mileage, etc...

[jcool]

Cujotom thank you for explaining how your fixed your cav. I have a 95 cav 2.2 and had the same surge problem. I tried everything. 2 new coil packs, spark plug wires, tps sensor, 2 fuel injectors, pcm and nothing worked. Finally I saw your thread and blocked both egr valves and YES it worked. SO for everyone out there if your car surges between 35 - 50 mph then the egr valve may be your problem. Any problems with the check engine light coming on?? Thanks again

[carena70]

[I don't know if your still looking for help with this problem but I had the same thing with my 98 Cav and tried all the same things as you even a new catalayic converter but it turn out to be the Transmission had a sticky valve so my mechanic changed the trans fluid and then added a bottle of lucas transmission treatment and after about 200 miles of driving the problem went away....