CPTslackass

The title says it all. This morning, I went to warm up the jeep. Starts up fine, idles in open loop. I come out about ten minutes later. We're up to about 150 on the temp gauge and yet we're still idling in open loop "1000". I go to goose the gas and the rpms drop. I then push in the gas and again, the rpms drop. It's wanting to stall. So I turn the jeep off. Go to start her back up and she just cranks. Wait two minutes and she starts. Goes into closed loop, all is fine. Then she goes back into a 1000 rpm idle. Hit the gas, she wants to stall. Then she goes back into closed loop again and all is well. Shut her off and restart her just fine. Should I try to cap off the EGR vacuum line?


1989 jeep Cherokee ax-15

cruiser54

Sounds more like a TPS going south.

CPTslackass

And she's five months old lol. Warranty.

CPTslackass

Ok, i did two things here. First off, I checked the TPS since i did mess with the butterfly yesterday. she was at .84. I took my voltage 4.84 and * by .17 which came out too .8228. So I set the TPS to .82. I also capped off the line going to the EGR. So far so good. I can tell you when i push on the gas, she really moves now. The power is very noticeable. Do you think any of those two *fixes* could have tackled my problem that I had this morning? Am I on to something?

cruiser54

Hook the EGR back up and see what happens.

CPTslackass

Ok, she did it again this morning. Here is what I noticed. It's only when shes in open loop *pretty much has to sit over night* When i first started her, she sounded like she was missing. No black smoke coming out of the tail pipe. You hit the throttle, she trys to stall. if you hit the pedal real good the engine will go down to around 100rpm but give it two seconds and it will rebound back too 1000rpm. She will continue to idle at 1000rpm no matter how hot the engine is. Here's the really funny part, you turn her off. She will not restart unless you floor the pedal *telling the computer to disregard some sensors* and then she will start. She will also idle at 700 and you are free to move about the country. Could it be as simple as me needing to replace the renix computer? It seems as if open loop isn't working correctly and it doesn't want to change to closed. Once it's in closed, you're good until you let it sit over night *longer than 5 hours* The ONLY sensors that arn't new are the crank *tested per cruisers test 4.68 volts avg* and the stator. Even with the stator unplugged, she still won't start. I have the egr plugged right now so I think I just ruled the EGR out.

PS, it did not start dong this until i pulled the butterfly back to fully close off the TB so the IAC only controlled the idle.

cruiser54

ONLY sensors that arn't new are the crank *tested per cruisers test 4.68 volts avg*

This doesn't make sense to me.

jakbob

x2. i think he is talking about the TPS... i dunno...

CPTslackass

Somewhere in your crank sensor test, you said to hook the volt meter up to the crank sensor and crank *volt meter set to AC* and I registered around 4.6 volts on avg *never dipped below 4*

DFlintstone

Typo? CPT, it's < a volt, (AC from the CPS). .5 + would be nice.

I believe there is a difference flooring it cranking as opposed to running. Cranking the injectors should stop. Running at more than 70% throttle it will ignore some sensors and go like hell.

I've been thinking of checking both my engine and intake air temp sensors, only because I'm (gradually), looking to epitomize my MPG, and it sounds pretty straightforward.

CPTslackass

I could have missread my volt meter then. It auto tunes to the volts and adjust the reading. I just know it read around that range lol. That is the CPS that I tested.

Why is it when it's stuck in open loop and you shut the jeep off, it won't restart until you floor the throttle pedal? Once the engine fires, I back off the pedal. If you don't hit the pedal, it'll just crank. Once the computer is in closed loop *which you have to shut the engine off and floor it to restart it to even get it to go into closed loop* you can restart it all day. Doesn't make a lick of since. That's why i'm thinking the computer. It only started this once i fine tuned the TB to even get it to idle at 700rpm in closed loop. As of right now I got the old butterfly stop screw out, put a new one in and now I have the idle "set" to run at 1000 warm. Waiting 5 hours for the Jeep to 100% cool off too see if this "hides" the cold start issue.

cruiser54

Keep us informed. IAC sticking closed?

CPTslackass

Well, it's brand new. I do have the old one though. Can I just watch it run by taking the air box hose off or would that cause the idle to go whacky?

DFlintstone

Just some thoughts:

If I thought I was flooded, I'd floorboard it to cut the fuel and provide Max air.

I found my MAP tube to be a delicate POS. (it needs to be flawless, or it could flood)

Because the CPS is such a trickster, I would want to see a reading (ACV, from the unplugged CPS, cranking), that made sense. My "cheapometer", only reads 10ths. Would like to up-grade to (two digits). You are talking three digits...

CPTslackass

Can i block the vacuum tube to the TB and put a T in the HVAC vac line and run a line up to my map to do away with the plastic ****?