Engine Start Up/Idling Issue

[rebelseageek]

So as of recent my 05 Wrangler will not start up properly and when it does it idles weird for the first 10 minutes or so until I get it running. Occasionally once I do get it running it will still fluctuate while idling at a stop or whatever. What further confuses me is it also idles so weird that if I let off the clutch to try and apply gas it seems as if it wants to stall but doesn't. Not sure if that last part is related but putting that out there in case its relevant. Any thoughts on how to fix this? It also has a check engine light that keeps popping up for the TPS (Throttle Position Sensor) and CPS (Camshaft Position Sensor). I would clear it but it keeps popping up because of this so its just pointless until I get this resolved.

Oh also I forgot to mention I got the battery and alternator test and they checked out fine. I'm ordering a new engine coil and new spark plugs.

 

[03coloradowrangler]

I would consider taking care of the 2 cel codes first. they are tripping for a reason, replace those parts first rather than putting them on the back burner while you toss miscellaneous parts at it in the meantime.

your TPS is involved with idling/engine speed as well as your CPS. the coil and plugs seem like additional potentially unnecessary expenses atop of the issue you are getting service code indicators pointing you in the direction you need to head first.

as for parts, id select oem sensors if at all possible.

 

[Modoc Guy]

I’d replace both the TPS and CPS if it’s throwing codes for them. Only OEM.

The spark plugs are a good idea, and if you’ve already got the coil, you could put it in. But that’s probably not the issue.

You might wanna clean the IAC. There’s a thread on doing that in how-to guides I think.

That’s how I’d start.

 

[rebelseageek]

I would consider taking care of the 2 cel codes first. they are tripping for a reason, replace those parts first rather than putting them on the back burner while you toss miscellaneous parts at it in the meantime.

your TPS is involved with idling/engine speed as well as your CPS. the coil and plugs seem like additional potentially unnecessary expenses atop of the issue you are getting service code indicators pointing you in the direction you need to head first.

as for parts, id select oem sensors if at all possible.

Yeah after being told im dumb by a few people (not here lol) i think im going to start with the sensors being thrown.

 

[rebelseageek]

I’d replace both the TPS and CPS if it’s throwing codes for them. Only OEM.

The spark plugs are a good idea, and if you’ve already got the coil, you could put it in. But that’s probably not the issue.

You might wanna clean the IAC. There’s a thread on doing that in how-to guides I think.

That’s how I’d start.

Sounds good thanks for the tip. Ill start there instead of throwing money at a coil and plugs.

 

[03coloradowrangler]

The oem Coil rail generally last usually a very long time. Aftermarket coil rails have been known to fail shortly after replacement.
As for the plugs, it doesn’t hurt to pull them and look at the gap or burn pattern.

But in all honesty I’m thinking the tps and cps will do a lot to fix your issue.

 

[reddvltj]

Before you replace the sensors, if you have a DVOM it might not be a bad idea to check to see if they're in fact "bad". Just because that's the code being triggered doesn't mean the sensor is bad.

 

[Modoc Guy]

Sounds good thanks for the tip. Ill start there instead of throwing money at a coil and plugs.

The IAC is easy and could contribute to idling issues. Just be careful not to damage the gaskets when you’re cleaning it.

 

[pagrey]

Plugs is the first thing I thought of. They are cheap and if you haven't replaced them it's a good idea. The TPS and CPS sensors use the same ground and voltage reference, that's the common element there. I'd check really carefully all the grounds, especially the one on the back of the block by the oil filter and the firewall. Then give the battery cables a check, they should look perfect and free from corrosion. Grouped codes for sensors is almost always wiring. Plugs, ya I'd do those too.

 

[rebelseageek]

Sorry for such a late update. Things came up in life. I put the two sensors on order they should get here by the end of the week. I’ll update when I install them to see if that fixes the issue.

 

[rebelseageek]

The oem Coil rail generally last usually a very long time. Aftermarket coil rails have been known to fail shortly after replacement.
As for the plugs, it doesn’t hurt to pull them and look at the gap or burn pattern.

But in all honesty I’m thinking the tps and cps will do a lot to fix your issue.

Yeah I just made an update with what I’ll be doing and I’ll be sure to post an update the second I install them.

 

[rebelseageek]

Before you replace the sensors, if you have a DVOM it might not be a bad idea to check to see if they're in fact "bad". Just because that's the code being triggered doesn't mean the sensor is bad.

That is a fair point. Unfortunately I’m dumb and already placed the order for the sensors (already shipping). So I’ll check the sensors before I install the new ones just in case I need to return them.

 

[reddvltj]

That is a fair point. Unfortunately I’m dumb and already placed the order for the sensors (already shipping). So I’ll check the sensors before I install the new ones just in case I need to return them.

If you test them and they prove to be bad, you'll have the new ones there. If they test out to be fine you can either return them or hang on to them for spares... Win/win!!

 

[Jerry Bransford]

If you test them and they prove to be bad, you'll have the new ones there. If they test out to be fine you can either return them or hang on to them for spares... Win/win!!

Testing them with a VOM is going to be difficult without knowing what they should measure, ohms-wise. Do you know the normal ohm resistances for either sender? I do know that I've had a bad TPS sensor on two different Jeeps and both caused a really bad idle/off-idle issue.

 

[reddvltj]

Testing them with a VOM is going to be difficult without knowing what they should measure, ohms-wise. Do you know the normal ohm resistances for either sender?

Not off the top of my head, but it shouldn't be too hard to look up.

 

[Jerry Bransford]

Not off the top of my head, but it shouldn't be too hard to look up.

Harder than you may think, I remember trying to find those numbers once.

 

[reddvltj]

Harder than you may think, I remember trying to find those numbers once.

You could also check the voltage sweep while they're still installed.

Edit: or since he has new sensors on the way already he could check resistances on those before he installs them then compare the two separate readings.

 

[Jerry Bransford]

You could also check the voltage sweep while they're still installed.

Edit: or since he has new sensors on the way already he could check resistances on those before he installs them then compare the two separate readings.

Yes, they're nothing more than a basic potentiometer of which I have tested and replaced many over the past 50+ years.

 

[rebelseageek]

Update: I installed the new throttle position sensor and to no avail it still has issues idling/starting up. I didn’t get to install the crank sensor due to Washington weather and it down pouring. But hopefully that helps fix the issue. If not I’m at another loss.