I cant seem to pinpoint my problem here. 2001 with a rebuilt 4.0, NV3550, progressively gotten worse these past weeks. I go to start it up, and the rpms go straight to 750, it used to go to 1200 and fall to 750 now it goes straight to it. It got worse, Rpms getting lower and lower each time. Now it will do that sluggish startup and fall to around 250 rpms and barely stay alive. When I drive it around and go to shift my rpms fall so fast its almost like someones killing the motor and it makes my shifts really clunky(if that makes sense). But heres the catch, its not 100% problematic, sometimes it will start normally and idle normaly(rarely) but now it just bogs down under 500 rpm and I have that issue when I push in the clutch. I put new spark plugs when I rebuilt the motor I tried jerry's trick using 1/3 can of throttle body cleaner into the IAC, took it out and cleaned it too. Im not throwing any codes. What am I missing here?!
Strange low idle issue
- Thread starter D M
- Start date
What did you take out? Was the engine at idle rpms while you sprayed the cleaner into the TB? Perhaps a bad or dirty IAC, TPS (throttle position sensor) maybe a bad upstream O2 sensor.
yes, i left the engine at idle so the carb cleaner would not surpass the IAC( i know how that part works) I also pulled the IAC and cleaned it thoroughly AND the housing it sits in. Can I clean the TPS? Also where are the upstream o2 sensors? Quick note: I dont know if it is important, but my rpms were so low, just the slightest bit of carb cleaner kept killing it.
The TPS is a sealed variable resistor and cannot be cleaned as the IAC can. The two upstream O2 sensors are just above the pre-cats.
Is there any way I can check the sensors? As I said earlier Im a bit confused because im not getting any codes
I'm not necessarily suggesting you have a bad O2 sensor but they seldom cause a CEL when they go bad. The PCM has a hard time telling when they're giving bad information.
I hate to say it but now she wont start on me. The jeep just cranks and cranks, got it to start for a bit but had to keep hitting the gas to keep it alive if I had the clutch in.
She started, I usually do the on off trick 3 times anyway since my starter(i think) cranks a long time and wont really start unless i do that. Here is a video of what happened. It goes to like 500 and starts bogging down again wanting to stall
IMG_0230.mp4
(sorry for bad quality I dont know why it did that, I used my Iphone )
Any specific one? Or will any one from amazon do the trick. I have the 19 gallon tank BTW.
If you're handy and aren't afraid to get inside of the fuel pump assembly, I'd buy the Bosch fuel pump module. If that scares you I'd go with the Delphi fuel pump assembly. Both are on Amazon and Rockauto.com. Avoid buying store brands, Spectre, or Airtex. The entire fuel pump assembly is no longer available from Bosch.
So I ended up going with the delphi, went right in no issues installing. Started up just fine normal 3 cranks. It fixed the idle issue temporarily. I come to stops at stop lights and it idles below 500 rpms. I was at a friends house and it started then died, then just kept cranking. I gave it gas to start it while cranking and it was running but I had to keep giving it gas or it would die. I got it home, but I noticed something this morning, my dash lights would brighten up if I gave it more and more gas, so do you think this could be an alternator issue too?
Might be the battery.
I've had two friends w/ Cherokees that had funky gauge needles bouncing everywhere, wouldn't stay running at idle. Ended up a bad cell in the battery. The stock alternators aren't big enough to run the whole system on their own at idle.
Other than that, I'd say spray some snake oil, er , um Sea Foam in the intake and clear some crap out.
Just checked the battery, I believe it was 12.47 or 12.67 while the engine was off(key was not in the ignition) If it is any help to mention, my check gauges light occasionally beeps at me when I start it up warm, but I think its because the oil pressure gauge stays at 0 for like 5 seconds of running
shit, do you think It could be an alternator problem as I mentioned before due to the lights lighting up on accel?
Where were meter probes touching when you measured the battery voltage. On the connectors or were you measuring from the battery posts themselves inside their connectors?
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