New GTP problems.

[Booba5185]

Hey everyone,
I just picked up a 2000 GTP, and I'm loving it so far. Easy to work on, fast (ish), all the cool gadgets, etc. Anyways, car has 227,000 miles on it, so I'm going through it doing all the typical maintenance stuff. I've changed the S\C coupler, new belts, oil change, coolant flush, seafoamed, new thermostat, new 02 sensor, new ECT, and new plugs and wires. It still has a bit of a rough idle and it runs pretty hot. It will randomly throw a P0303 misfire code (which is why I did new plugs\wires), but I don't feel it misfire, seems to run fine. The PO replaced the coil that cylinder 3 runs off of, so I'm assuming that is not the problem. Whats the next step? ICM?

Also, the e-fans are not working, If I hot wire them, they work great. I checked everything up to the PCM, relays, fuses, etc. In my research online, the PCM provides a ground to the relays to turn the fan on, so I disconnected the PCM, grounded pin 5 and 6 (one at a time) and the fans turned on exactly like they should. Fans don't come on at all (A\C on or not). I've also gone around and cleaned most of the grounds, there's a few inside the cabin that I haven't gotten to yet, as well as the main ground by the battery.

I'm not new to wrenching at all, but I am new to Pontiacs, I've always worked on Fords, so this is a new field to me. I don't mind spending the money on a new PCM, but I want to make sure it is the problem before I do. Does anyone have any feed back on input on these 2 issues?

Thanks for any and all help you guys can provide.

Edit: The PO (genius BTW...) had a wire leading from the cruise (brown wire) to the e-Fans (Grey Wire). That has since been removed...not sure why he did that.

Edit 2: I read online that if you unplug the ECT the PCM should not only throw a code, but also have the fans on all the time. I unplugged it and nothing changed, no SES and no fans. Does this mean my problem revolves around the ECT? When the A\C is turned on is the ECT bypassed (when it comes to the e-fans)? My temp gauge works fine; I know there are 2 sensors inside the ECT, one for the PCM and one for the gauge.

[Booba5185]

A little bit of an update, I went into the diagnostic mode of the CJ2 (digital climate control) and checked the ECT through that. The gauge was roughly 100 degrees higher...CJ2 showed 144 degrees before I shut it down because the gauge showed around 250 degrees. I'm sure it was wrong, but I'd rather not risk my motor.

Is my ECT bad? This would be the second new one I put in, the first one made the temperature gauge peg all the way bass hot the second I turned the key.

[codyAK]

A little bit of an update, I went into the diagnostic mode of the CJ2 (digital climate control) and checked the ECT through that. The gauge was roughly 100 degrees higher...CJ2 showed 144 degrees before I shut it down because the gauge showed around 250 degrees. I'm sure it was wrong, but I'd rather not risk my motor.

Is my ECT bad? This would be the second new one I put in, the first one made the temperature gauge peg all the way bass hot the second I turned the key.

Sounds similar to what my ECT is doing.. My guess right now is a bad ECT sensor unless someone can give me another answer.
http://www.grandprixforums.net/2-24-...ues-62870.html

[dsmuts]

Check your fuse for the fans and the relay

[TexasTanker19kilo20]

Welcome to GPF, hope you get it sorted. Someone should be able to figure this out for you, it's over my head.

[Scottydoggs]

did you bleed the air out of the cooling system? via the bleeder a top the t stat? if not the temp sensor may not be getting any coolant to it. or maybe a bad temp sensor.

also does the a/c work? if the compressor dont turn the fans wont come on like they should. as far as a/c is concerned.


the misfire could be a bad icm, under the coils. some times you can take the coils off and clean it up (the icm) and it will work. you can also test them.

and the rough idle, check for vac leaks, the T's like to break, under the sc snout, and the one on the fpr.

the fat vac tube that curls back off the TB to the evap also likes to hide a crack as well.

if you find your self needing a new vac line on the vac tree on top of the sc, cut the line first with a razor then remove, or your sure to break that tree. its plastic, and been through a how many heat cycles? yeah, its brittle.

the old fashioned carb cleaner sprayed around the vac lines and sensors will make the idle jump some if theres a leak. you can pin point it like that.

[Booba5185]

Thanks for the responses, I've replaced the vacuum lines from the TB back to the EVAP solenoid on the rear of the motor, as well as the T and lines leading to the MAP and FPR. I have my boost bypass solenoid bypassed for now, but the bypass valve is still functioning. I did bleed the coolant system via the bleeder screw (an ingenious idea BTW), and all fuses\relays have been checked. I'm thinking more and more that it's the ECT or the fact that I used RTV on the ECT when I installed it. I'm inclined to believe the CJ2 temperature, because if the motor was at 250+ degrees, a lot of steam would be coming up from the engine, it's 31 degrees outside right now.

I'm kind of confused by the instructions for the CJ2 diagnostic mode...
-12 Engine Coolant Temp -60 degrees 80=104, 95=131, 100=140 Peak@135°F
Mine got up to 144, so what was the temperature really? 204?

[Booba5185]

Yep, it's a bad ECT. I just drove 80 miles with CJ2 in diagnostic mode, temp got up past 150 when I got home, and the fans were on. Temperature gauge was pegged past 260. No SES light yet either, maybe the misfire code is fixed as well. I didn't get friendly with the gas at all, trying to keep the MPGs as high as I can.

Now to check out the cruise\ABS situation. All wheel bearings appear to be plugged in and the harness is fine as well, any ideas on where to start from there?

[RAGEN]

Try using an infrared thermometer to verify the ECT sensor. That way you can know for sure what your engine temp is...my 2cents

[BillBoost37]

Infrared? This guy has a CJ2 thingee, that most of us never consider looking at.

Since you have two ECT's built together, I would have scanned the pcm temp. The PCM and gauge should be reasonable close in temp. Fans don't kick on until at least 216F or if the AC actually requests them on. If your AC system isn't up to par, the request may not be happening. Sounds like you have determined that either the ECT or your cluster gauge is bad.

Please elaborate on the cruise issue. It sounded like he jumped a ground from cruise on/enable over to the fans to make them work when he wanted, which you since removed. You didn't mention much beyond that though.

Likely you are enjoying the lack of plumbing and vacuum lines GM vs Ford. You may notice a lack of inline connectors as well. Takes a lot of the easy clean, reconnect out of the diagnosis.

[RAGEN]

What is a CJ2?

[BillBoost37]

It's either the tool or a parameter in the climate control that he got the engine temp from. Pretty deep stuff compared to where we typically go for the temp.

[RAGEN]

Sorry. I usually just use my handheld thermometer if I question my temp gauge. But if the ECT sensor is bad, how would that feature get an accurate reading on these cars?

[BillBoost37]

Well, there's three places that temp is possible to be found.

1. PCM (seperate feed from dash gauge)
2. Dash gauge
3. Climate control (not sure which feed this uses, probably pcm)

If you have a scanner, you can typically read pcm, if you have a super deluxe scanner you can read climate control info/codes.

[RAGEN]

I see. I guess it's time to further my own education too and learn some about these systems in case I ran into these problems with my cars. Thanks for the quick lesson.

[Booba5185]

I believe the CJ2 uses the same ECT portion as the PCM to check temperature. To get into the diagnostic mode you push both knobs and hold them for 10 seconds until you see -00 on the screen. Turn the left (driver) knob until it says -12, then turn the right (passenger) knob and it will display your ECT temperature.

I hear ya on the For vacuum lines, I wrote this: Replace Plastic Vacuum Hoses with Rubber - FSB Forums

I haven't looked into the Cruise situation much yet, it's after I fix the ABS. The wire lead from the brown wire in the connector that plugs into the cruise control servo (has the cable coming out of it that goes to the throttle body), and had it connected to the grey wire of the fans. I believe (off the top of my head) that the grey wire is the low speed on the fans.

I want to fix the ABS and Trac control lights first because frankly it's more important to me. Also, I've heard that with the ABS light on Cruise can be disabled.

Thanks again for all the responses guys.

[Scottydoggs]

the abs/trac off light. first start off with jacking each wheel up, then grab the tire at the top, push and pull it firmly, you looking for some movement. should be rather tight feeling. you can also watch the rotor where it meets the brake caliper to see if its moving.

then clean the plug to each hub, and inspect the wires that run along the lca's they get torn up sometimes.

if you cant find any of these free checks to be the problem, its best to pony up and pay to have the abs scanned, or you could be just tossing money at it.

[Booba5185]

I've checked all but one of the wheel bearings and connections and they seem fine. I'm going to trace as much of the wires I can to see if there is a break in the connection somewhere. I remember hearing about being able to check the sensor in the wheel bearing with a multimeter, and if I can find those instructions I will check all 4 of mine. If they all 4 pass, then I'll have to have the system checked.

[Scottydoggs]

sounds like a plan. ive heard of testing the ohms of the sensor as well, i have no idea how to do that. i truly hate electrical problems.

[Booba5185]

I'm an electronic Guru, I've added 23 or more relays to my 1989 F150, e-Fans, headlights\fog lights (13000+lumen on the front of my truck, haha) etc. Once I find the instructions for testing the sensors I'll post them here.