96 Bonne won't start at certain cold temp?

[Briancada]

Yesterday morning my 96 Bonne wouldn't start. This may seem wierd but the outside temperature was 39 degrees. The car would turn over but would not fire. This happened last fall twice. The outside temperature was almost exactly the same. Once it got warmer outside the car started right up like nothing was wrong. I had a check engine light last fall when I took it to the mechanic but they never told me what the code was. They said it only needed a tuneup and $300.00 later I had a tuneup. Two weeks later I had the same problem but it eventually started. It happened again yesterday and I had a check engine light and this time I had it scanned with my friends code scanner and it came up with Throttle Position Sensor Low Voltage. We cleared the code and it has not come back. Car starts great now but would like to be able to get to work on time everyday, not dependent on outside temperature. Any ideas would be helpful.

[GMMerlin]

Most likely your TPS has an internal fault that is temperature sensitive.
A TPS going low will cause a hard or no start problem.
I would go ahead and replace the sensor...if it is adjustable, set it to .4 volts

[Briancada]

Thank you. I will do that this weekend and will post the results.

[Flatrater]

I agree with Merlin either you have a bad TPS.

And just for FYI their is no such thing as a tune-up trouble code!!

[Briancada]

Originally Posted by Briancada

Thank you. I will do that this weekend and will post the results.

Replaced the TPS sensor in the Bonne this weekend. It was a snap. Hopefully it will fix the problem I have been having.

[bridget36907]

Originally Posted by Briancada

Replaced the TPS sensor in the Bonne this weekend. It was a snap. Hopefully it will fix the problem I have been having.

Did it fix your problem

[Briancada]

Originally Posted by bridget36907

Did it fix your problem

Actually it didn't. After replacing the TPS sensor this happened to me again a few months later with the exact same symptons.
I have since replaced the intake air temperature sensor and the engine coolant temperature sensor because in one manual those temperatures reading greater than 10 degrees apart will not allow the ignition sequence to occur. That didn't fix it because it happened to me again this morning. I have taken it to a different mechanic and they also have found nothing. No codes logged in the computer.
Any other ideas?

[LMP]

WOW...I just noticed this thread was a long shot.....what happened during this 18 months interval?

[O.P]

I'm having the same problem, I replaced ans set TPS, CPS, Igntion module, fuel pump, fuel pressure regulator, O2 sensor, CTS, .. I hope someone knows whats up

[GMIvan]

Just a thought had the same concern that was temperature sensitive and found that at that temp the MAF would have 0 g/s reading during cranking and had an almost zip injetor pulse width. Do you have access to a scan tool? If so monitor the MAF reading when the ambient air tamp is such to duplicate your concern. If you have a K&N air filter toss that sucker to the curb install a new MAF and air filter and check out if you have the same concern.

HTH

[dmccr]

Long post - suggestions for you at the end, but please also review my continuing problem to see if you have other ideas!

I Googled re: this problem, and found this thread -

I'm having the same issue (91 Bonneville), and it is maddening!

I've checked and/or replaced:
O2 sensor
CTS (coolant temp sender)
Crankshaft sensor
Camshaft sensor
Fuel pump
Fuel sender
Fuel filter
plugs
Cleaned all ground points
Neutral safety switch
Dome light
Fuel pressure
Ignition module tested by a parts store many times in succession (to warm it up).


Of interest:
*I used a good scan tool for some time while trying to diagnose the problem (after most of the new parts were installed). NO codes were ever set, and all values appeared to be "in range." Unfortunately, it never failed to start while I had the scanner!

*WHEN it runs, it runs very well, and will start right back up if I shut it off. The problem occurs only after sitting many hours, at which time it cranks fine but doesn't kick in.

*Another problem which may/may not be related: sometimes the cruise control spontaneously quits on the highway, but that is quite infrequent.

*I discovered my ECM (engine control module) was not properly seated in its' plastic mounting bracket. The connections were all fine, but the unit was loose enough to lean forward and contact ground points. It is important that the ECM case not be grounded, since many sensors provide their readings by transmitting a ground signal to the ECM.

*This car was stolen once and hot-wired, if that is relevant.

*I have the actual OEM service manual and up-to-date Technical Service Bulletins (TSBs), which I've scoured many times. I would reproduce the recommended diagnostics for you, but it is dozens of pages. If there is interest expressed, I might scan some of it for you.

Possible fixes I plan to explore further:
1) Learn to use a "noid" to determine if the injectors are firing.
2) Use the spark tester (purchased yesterday) to see if there is spark.
3) Replace the air filter (it is dirty, but doesn't look that bad)
4) Check for exhaust back-pressure using a vacuum gauge on the intake. (I've read this suggestion elsewhere).

Suggestions for others (now that I'm a little bit wiser):
***Note that most of these are free or cheap!***
1) Check for actual spark. I'll assume you've already inspected the wires and plugs. (I believe I should have checked for spark FIRST rather than last... I've just never done it, and did what was familiar first).
2) Check for fuel pressure. Use common sense, but the simplest test for pressure is to turn the key to the run position (engine off) for two seconds, then turn it off. Unscrew the valve cap on the top of the engine (NOT THE A/C LINE elsewhere). Use a rag and shield your face, then briefly press the valve stem. Fuel should squirt (not dribble). If you are the least bit hesitant, fuel pressure testers are not that expensive, clearly safer, and give you an actual reading (should be about 42 psi).
3) Check to see if the injectors are being told to fire. Like in #1 above, I should have done this at the beginning, I've just never used a noid light.
4) Check your ground points! a)The main engine ground is right underneath the ignition module/coil pack. It is a little hard to get to, but worth cleaning up. b)The ignition module grounds to the mounting bracket. The factory manual instructs you to use dielectric grease when installing, to protect the ground. c) Smaller grounds are located around the engine compartment, just look for the wires that are screwed to the sheet metal. d)In the trunk (mine was VERY bad) under the carpet on the passenger side floor just forward of the antenna.
5) I don't know about you, but I seem to skip checking the condition of wires too often. Example, when I changed the O2 sensor, I realized that the insulation had been worn through to bare copper several places! Take the time to follow all those wires around with your fingers and make sure they are intact. Check the connectors for corrosion.
6) Many parts stores will now test many components for free. I suggest having them test your ignition module (label all those wires when you take 'em off). Ask them to run the test about 10 times in a row, until the module feels quite warm. That can help diagnose temperature-related problems. Since our problems are with cold, I may yet put my module in the freezer and keep it iced down until they test it. (Do I have to tell you... keep it dry!)
7) Scan Tool: I'm fortunate to have a store that gives out $300 scan tools on loan! Of course, you pay up front, but get a refund when you return it. If you are not so lucky, most parts stores will now scan your computer for you. Remember that NOT ALL malfunction codes cause the "check engine" light to come on. See what there is to see, but remember that scan tools may list a problem with a component that is actually good. i.e., poor air/fuel mixture can result in an O2 sensor code being set. The sensor isn't bad, the fuel mixture is what needs fixing!

Hopefully this tome has given you some ideas... I'll look forward to your replies!

[dmccr]

After my last lengthy post, I tried the spark tester and noid. Both appear fine. Anyone have another suggestion? It doesn't seem reasonable to think all six injectors became plugged at the same time...

[O.P]

I have been battling the same problem. I just sorta figured out a half-ass solution. I disconnected the CTS wire, I think its a green with blk stripe. This, for me fixed my problem, the only thing is that the temp guage doesnt work. I might add that in the past I had replaced the CTS 2 times, along with everything else you mentioned above. Like I said, I've been battling this with my car since Sept 2003 (look in the archives). Let me know how this turns out.