My 88 GTA 5.7 has poor driveability. The new spark plugs are fouling up, black and carboned, only after being in for a few days and only after 1 or 2 miles of driving, so it must be running rich. Removed the air intake and smelled lots of gas odor.

code 15 : coolant temp sensor low voltage.
I noticed that a wire that goes to a sensor right above the front drivers side spark plug is not attached to that sensor. Is that the CTS ? I suppose that would explain the code 15, right ? would a disconnected cts cause driveability problems ?

code 21 : TPS volts high. This could be making the injectors too rich ? How much does a TPS go for ?

code 33 : MAF sensor. I really think my mech replaced my MAF with a bad one. (lawsuit city, that's another story) The ring inside is all rusty and there are seeds and pine needles in it, like it was lying around a junkyard. It wasn't like that when I took the car in. urge to kill


code 53 : high system voltage (but only for years '93 and up, in my manual. hmmmm. ALternator putting out spikes, maybe? The voltmeter always reads 14 when the car is running. This 53 was the only code I was getting at first.Then I took the car to my mech, who put new plugs in, and now I am getting these other 3 codes.

The driveability symptoms are a) stalling
b) cutting out for a second and restarting c) it drives smoothly if I keep it at about 40 mph or higher, but any lower speed has roughness, and it will stall at about 10 mph when slowing down.

Thanks for anyone helping me out here. I have the car back from the nearly useless mech, and in my garage, and I am ready to fix it right.

Thanks


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88 GTA Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

Check the ground wires at the back of the heads.

 

For economy sake follow this diagnostic approach.

Replace the CTS, cheap 10 bucks. If it is not functioning it can cause the ECM to think your car is frozen, enrich the fuel mixture, prevent your car from going closed loop, and prevent your TCC from locking up which will send your MPG to squat.

Then replace the MAF Burnoff and Power relays and do the fuel pump relay at the same time (app. 30 bucks total). Even if this is not the problem you will have fresh relays.

Disconnect battery to clear codes and recheck for 33.

Providing your connections are clean to the MAF and your air connections are tight (Air Cleaner to MAF to Airbox to Bellows to Throttle Body then you will need to replace the MAF (140.00 bucks reconditioned Bosch - 1 year warranty).

Make sure your Airbox Duct has no hidden cracks....they are bad about cracking on the seams and it's hard to see.

Disconnect battery.....reconnect.... check for codes........ come back and post results.

 

Does your car have VATs? Don't recall on the '88, but 53 is VAT's on my '89.

And yes, with no CTS signal, drivability will suffer.

 

FYI - The coolant temp sensor that you are referring to on the driver side head, between Cyl #1 and Cyl #3, is the sending unit for the guage or idiot light in the car. It does not provide the input for the ecm as far as coolant temp goes. The sensor that mounts in the front of the intake manifold that has a oval shaped connector with black and yellow wires is the CTS for the ecm input. The other sensor in the front of the manifold is actually more of a switch and it controls the cold start injector. Both of these sensors are under the throttle body, near the heater hose that goes from the lower intake manifold to the throttle body, and are threaded into the manifold itself. The one that you should verify the working condition of and/or replace (the CTS) will result in the loss of some coolant upon removal which is a good time to perform the Throttle Body Coolant Bypass mod (a tech article exists on this site).

good luck.....



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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, K+N cone, AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Hotchkis STB.

 

does anyone else realize that all the codes have to do with VOLTAGE PROBLEMS..
now that i've said that what does it mean?

secondly i would call the mechanic up and scream at him,, pine needles in the maf, what the f-uck? dont pay this guy a dime.

code 21 and 33 have to do with the same thing,, did you check the tps voltage yet?

[This message has been edited by ron rizzotti (edited July 14, 2001).]

 

Matt got that right, I missed the fine print...beter get my refund from the Evelyn Woodhead course

Ron brings up a good point, and relates to what madmax mentions...*most* voltage problems are due to poor grounds.

 

Wow, lots of good information. SO far, I have disconnected the maf, and the car runs better, but still is rough.

No, I have not tested the tps. I suppose I will have to get a voltmeter. Can I check it without the car running? I think i am fouling my plugs each time I start it, so I don't want to run the engine too much.

I have a hundred other questions, but for now, let me ask whether an overvoltage (53) is burning out these sensors. If I replace the tps, for example, will the overvoltage just burn it out again ?

Thanks

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88 GTA Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.