I have a 94 POS-15 Jimmy 4.3 (W) and when i start it when its cold it idles a little rough but the warmer the engine gets the worse it idles. When you drive it down the road it runs fine as long as you dont stop, then, it gets rough again. It smells like its running rich also. The Dash is digital and the only thing that works is the speedo and the check engine light, etc. No tach and no temp guage. Does any one know if the temp guage goes out if the ECT will still send the signal to the ECU? or Does anyone have an idea of what the problem might be or has anyone had this problem?

Thanks for the help...


Here is what i have changed:

FPR
Distributor cap
Spark plugs and wires
TPS
MAP
and oil because of the FPR

 

Your temp guage is run off a 13/16 sensor that is located between and above the 2 front spark plugs on the passenger side of the engine. That "Coolant temp sensor" is about 40 bucks at the parts shop. Have teflon tape on the new ones threads before you pull the old one cause the green stuff comes puking out the hole when you pull the old one out.

Make sure that you have the sensors connector hooked up, mines problem was that some bonehead broke the plug off the top where the plug snaps on and the wires melted on the exhaust manifold. I just fixed the wires, and got a new sensor and it was all good.

My dash works fine exept for the speedometer, sometimes it shows, sometimes it doesnt.

Your rich smell sounds just like the problem that I was having with my blazer before it got towed home. Was running rought sometimes, and I had to deather the gas to keep it running, then it just died. Wouldnt want to restart when shut off. Poor gas milage.... poor poor poor gas milage. I changed the FPR and still wouldnt start, so when I pulled the spider legs out of the holes I found that they were pissing fuel out the tippets... I got a junkyard spider installed, turned the key and they didnt **** anymore and fuel pressure would hold, but then the rain started and i havent been able to put the intake back together... So I just shut the hood and wait.

 

yea, it runs ok just not at idle. do you know if the Coolant temp sensor sends the signal to the guage then the ecu, or does it send the signal straight to the ecu then to the gauge? the guage doesn't even light up at all. I changed the FPR because it was pissin gas in the oil really bad. Its not throwing any more codes or anything either. If the signal goes to the cluster before the ecu it would make sense why it isn't running right, but if it doesn't send the signal to the cluster first i don't want to change it if it won't do anything to fix the problem. I think im also going to take the cat off of it and check vacuum lines also and see what that does. It just seems like the ecu isn't getting the signal that its warming up so it isn't cutting the gas down. is there a way to check the coolant temp sensor to see if its bad since the guage doesn't work(like an ohms test)? if so what should it read?


Thanks for all the help i appreciate it.

 

Is the lightbulb behind the temp guage burned out? I remember reading that there is 2 temp sensors... the one on the passenger side is for the guage, and there is one on the thermostat housing for the ECM...

 

I'm not sure if the bulb is burnt out or not. to be honest i didn't know you could change them on a digital cluster. I read if you ground out the wire on the temp sensor in the block it should bury the temp gauge.

Did your blazer run ok going down the road? b/c it doesn't miss a lick when its moving.

 

Yeah mine drives great down the road, just when you come to a stop she wants to quit...

 

Well i was outside looking at the jimmy trying to find the coolant temp sensor in the front of the block by the thermostat housing which i did find. I noticed that the intake air temp sensor was laying on top of the water pump and it was still plugged in. So, the question is will that make it run rich i wonder?


i'm open to all suggestions. Thanks....

 

I think having it in a hot spot would do the opposite actually... I remember back in my rice rodding days that was a mod guys did was move the IAT to somewhere cold so they get more fuel in the motor... I dont know if it helped make more power or not, I never did it myself.

 

yeah, it probably isn't getting too warm where its at b/c of the air from the fan though. The darn truck wouldn't even run when i picked it up so i guess i'm making progress. Just not as fast as i hoped b/c one thing keeps leading to another. LOL... I guess i'll put the IAT back in tommorow and see what that does. Maybe if i get luck it will help, or not. Knowing my luck i'll be lookin for a stick of c4 soon to fix it, LOL...

 

I hear that... Im going to have to unhook my battery around the corner from the aircare inspection station to clear the codes, then pull in and see if I can pass the emissions test before the engine light comes back on... I have to get this truck insured on the 3rd so we have a vehicle... I would just do my toyota but some shmuck hit it parked the other day and now it needs body panels and bumper and lights before it will pass for mechanical... If I didnt have bad luck, I would have no luck at all... We also have a Ford Exploder with a broken flexplate that I am in no hurry to take apart and fix as I dont like that gaspig... And my S10 isnt even in this province yet, and it wouldnt pass an emissions test anyways with the smogger V8 in it...