Runs good cold But not hot

92legacyss · Post by **92legacyss** » Tue Dec 01, 2009 5:57 pm

So my car runs great for like 15 min and then once it is warmed up it sputters and jumps also has a rough idel, it had a rough idel once before but new spark plugs fixed that. Also my speedometer and odomerter stoped working the other night. anyone have ideas?

Post by **Legacy777** » Tue Dec 01, 2009 7:19 pm

You need to fix your speedometer first. The ECU does some funky things when it doesn't get a VSS signal.

I would check to see if the cable became unplugged from the back of the gauge cluster. If not, check the plug at the transmission. If all looks well, you can stick the end of the cable in a drill to see if the speedo will read.

If all that checks out ok, then you probably have a problem with the plastic gear in the transmission.

ericem · Post by **ericem** » Tue Dec 01, 2009 7:50 pm

Od how the speedometer AND odometer stopped. Both happened at the same time?? What reads the signal for rpm I think the crank or cam sensor??

Post by **Legacy777** » Tue Dec 01, 2009 7:54 pm

Odometer is hooked to the speedometer.

ECU reads the crank signal for engine RPM, and then has an output to the gauge cluster & TCU.

ericem · Post by **ericem** » Tue Dec 01, 2009 8:18 pm

Legacy777 wrote:Odometer is hooked to the speedometer.

ECU reads the crank signal for engine RPM, and then has an output to the gauge cluster & TCU.

wait odometer is total km isn't it LOL tach is rpm blah sorry mixed the two up XD

92legacyss · Post by **92legacyss** » Tue Dec 01, 2009 9:52 pm

No the speedometer is not the problem because it was doing this for a while before that went out. I thought i had a boost leak but i just redid all the pluming with silicone i am pretty sure its not the boost anymore. i am just not sure why it runs so good when it is cold but like shit when it is warmed up.

ericem · Post by **ericem** » Wed Dec 02, 2009 12:53 am

Maybe CTS??

92legacyss · Post by **92legacyss** » Wed Dec 02, 2009 2:14 am

I don't think it is the CTS all my hoses are clamped tight and no coolant loss or drastic change in temp plus the themostat and water pump are new

race_to_live · Post by **race_to_live** » Wed Dec 02, 2009 3:29 am

did you do anything with the timing belt? when i put a new belt on mine, i put it on a tooth off or so. but at the time i didn't know it. mine ran just fine til it got warm, then as soon as it hit some temp it just took a crap, and got worse the more i drove it. i know it doesn't sound like timing would do it, but it did for me.

tahiti350 · Post by **tahiti350** » Wed Dec 02, 2009 3:40 am

The coolant temp sensor (CTS) COULD cause the crappy running once the engien starts top warm up. If the ECU thinks the engine is cold, but the O2 and other sensors are saying it's too rich it's going to go into limp home....

Where are you located? I have the CTS I took out otf the wife's '90 wagon (problem there was the MAF, so the sensor SHOULD still be good)

edgeofvamp · Post by **edgeofvamp** » Wed Dec 02, 2009 9:29 am

when its cold, does it idle high?

Have you done anything to the dash?

Post by **Legacy777** » Wed Dec 02, 2009 7:13 pm

I would kind of lean towards the coolant temp sensor. They don't throw codes, and can cause the symptoms you are describing.

As for the speedometer, get it fixed. You will have other weird issues start occuring if it is not fixed.

92legacyss · Post by **92legacyss** » Wed Dec 02, 2009 8:44 pm

tahiti350 wrote:The coolant temp sensor (CTS) COULD cause the crappy running once the engien starts top warm up. If the ECU thinks the engine is cold, but the O2 and other sensors are saying it's too rich it's going to go into limp home....

Where are you located? I have the CTS I took out otf the wife's '90 wagon (problem there was the MAF, so the sensor SHOULD still be good)

I am in VA

92legacyss · Post by **92legacyss** » Wed Dec 02, 2009 8:46 pm

Allright looks like i am going to take the dash apart to fix the speedometer and the CTS

92legacyss · Post by **92legacyss** » Wed Dec 02, 2009 8:47 pm

edgeofvamp wrote:when its cold, does it idle high?

Have you done anything to the dash?

Yes it idles high when it is cold between 1000-1100RPM no i have not tuched the dash

tahiti350 · Post by **tahiti350** » Thu Dec 03, 2009 12:30 am

Coolant temp sensor thru CarQuest was like $28 new...

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Runs good cold But not hot

Runs good cold But not hot