TCC, IAC, Coolant Temp Snsr, & cars not strt'g up aftr 2

[timoiii]

I have seen several topics that seem to deal with a problem with some cars having problems starting after having been running only a short time previously and/or stalling when slowing down. One person mentioned that this problem was more noticable for them when the day was cold.

 

I had this problem for the first time a few weeks ago - for four days straight the temps in Kansas City were between 10-20F. And for four days straight I would drive 12mins to my house for lunch, the car would sit in the drive for 20-25min and then I could not get the car to restart. The starter was engaging the engine. The battery was strong (despite being old). Nothing made sense, because it would fire up in the morning just fine. At first, this didn't really bother me a whole lot as I would borrow my wife's car. My wife did not share my apathy.

 

The next week, the weather was warmer and I didn't have any troubles. Well, last week, I went through my usual lunch routine. I was driving back to work and my car stalled as I was slowing to make a turn. This is a symptom that others have posted, that hitherto I had not experienced.

 

After searching the forum, I found four possible reasons for the symptoms others and I had experienced:

 

1) A damaged/ruptured Fuel Pressure Regulator Diaphragm

2) A bad TCC Solenoid

3) A bad Coolant Temp Sensor

4) A bad/fouled Idle Air Controller - IAC

 

Costs of Replacement:

 

1) $99.99 - Napa, Advanced Auto Parts/Parts America (could not find the diaphragm only. price is for the whole regulator)

2) $23.49 - Advanced Auto

3) c.$9.00 - Advanced Auto

4) $29.99 - Autozone

 

I bought 2-4. After thinking about it, the Fuel Pressure Regulator would be something (in my mind) that would not be affected by temp. I could be wrong, but I'm thinking its either functioning or it isn't. So I just scratched that from the list. I'm not too keen on spending $100 before exhausting cheaper more likely avenues, first.

 

Since the Coolant Temp. Sensor had the word sensor in it and it was cheap, that was the first thing to replace, in my book. I had to remove the rubber pipe coming off of the air box and going into the throtle body to make the replacement easier. There were a few thing in the way that made the process go about a 1/5 or 1/6 of a turn at a time.

 

An aside - Somebody, posted a picture of their cutty or Grand Prix with a huge Northstar engine sitting under the hood. Can you imagine working on that?

 

After the temp sensor, I went ahead and replaced the IAC. When I removed that baby, it was fouled worse than the black, brown, and erroded plugs that I replaced in the summer (The previous owner had put 2 Bosch and 4 AC-Delco in there. I have no idea if they gapped them properly because the plugs were so badly erroded. On the plus side, at least 2 plugs were replaced before I bought the car. Who knows on the 4 Delco plugs). After looking at the IAC, it didn't matter if it was the culprit or not, it needed to go. Actually, there have been several postings mentioning that this can and should be periodically cleaned.

 

This would be a good time to mention something I am going to put into practice. Whenever I buy a used car, there are a few things that I will do instantly:

 

1) change plugs and wires

2) change O2 sensor

3) flush transmission

4) clean injectors

5) check IAC

6) check air filter

7) replace trans filter

8) replace fuel filter

 

Hoses, belts and fluids should have been checked when I look at the car before I buy, but clean fluids are not indicitive of good maintanence, just shows that the lawyer was smart enough to put a suit on his client and give him a clean shave and hair cut before he went before the judge.

 

OK, back on topic.

 

Oh, you may need Torqs for the IAC. It looked like everything on the throttle body used Torqs screws. I had to make a run to the store to make a 5 min replacement.

 

Regarding the TCC, I read where some people bypass some of their problems by just removing it. It was either a post or the service manual that said that the 3.1L VIN T cutty MUST have this plugged in to function correctly. Others have posted and the service manual mentions that a improperly functioning (or disconnected) TCC will cause poor fuel economy. A link from a post regarding this mentioned that if you are going to go through all of the effort to get to the TCC, in order to unplug it, you might as well replace it.

 

The good thing is that you may not have to mess with the TCC dohicky at all. It turns out that the Vehicle Speed Sensor (VSS), Throttle Position Sensor (TPS), & the COOLANT TEMP SENSOR provide input to the TCC (I got that from reading the service manual for a 1990 CS (I have a 1991, but the manual serves its purpose. Therefore, you might be wise to buy and replace the $9.00 Coolant Temp Sensor before you take the time & money to replace the TCC. I know I would rather not have to go through all of the trouble of getting to the solenoid. However, not knowing what the symptoms are for failures of the other sensors, you may decide that they should be replaced instead/also. As for me, I am going to hold out till I see what the results are after replacing the IAC and the Coolant Temp Sensor.

 

After I replaced the IAC and the Temp Sensor, I had the car relearn its idle. The car idled noticably smoother and quieter. It also drove a lot quieter. It is going to take a few days, maybe weeks, before I know if those two replacements did the trick, since my symptoms seems to show up only under specific circumstances.

 

I am concerned with fuel economy and will be replacing the PCV tomorrow (Someone tell me why they did not put that on the front valve cover! ). I may replace the TCC in a couple of weeks instead of returning it just to make sure that I am not missing out on saving a few more precious drops of fuel per mile.

 

I hope something was helpful. It was a rehash of several topics that I found when researching my cutty's symptoms. It seemed good to pull it all together. However, I am sorry for not going through the effort of quoting all of the different references I found today. I did try to let you know what was not original thinking (most everything). I will say that you should do your own research before you actually DO anything. My opionions are just that and I do not know that what I have read (or said) is 100% accurate. So please take care and responsibility for what you choose or choose not to do to your car.

 

Oh, just for reference, I have a 3.1L 1991 Cutlass Supreme, A/T, with c. 180k mi. It isn't pretty, but it gets me where I want to go.

 

Regards,

 

Timo

[sniperi311]

so were is the tcc solenoid at, ive got a 93 old cutlass supreme mfi 3.1, thanx

[timoiii]

Do a search on TCC solenoid. There is a post with a link explaining it. Apparently it is behind a side pan on the tranny. To unplug it you only have to remove the airbox to get to it (From what I understand). However to replace it is a little more involved. The link mentioned something about removing the driver side wheel and also jacking up the engine. Someone else will have to be more specific, as I have not researched it enough. Hopefully, this reply will keep the topic in view a little longer such that someone can better help you.

 

Timo

[Dustin Imports]

coolant temp sensor inside or outside engine...my dummy light stays on.