Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

1 - 3 of 3 Posts

·
Detail Oriented
Joined
·
3,174 Posts
Discussion Starter · #1 ·
2003 Sport 4.0L 5 speed

I have had several persistent codes on this TJ since I got her about a year ago.

I replaced the entire LDP/EVAP canister and filter rack with a known good one from my dead TJ. The code for the P1494 code it throws on occasion. (LDP pressure switch problem - electrical or the pump itself)

This was about two weeks back. The code persisted up to today.

The P0123 code (throttle position sensor voltage high) started up about a month ago and was persistent through two code clearings.

The P0171/P0174 codes (lean condition in both banks) has been a problem on and off for some time. The light has never cleared and the code is always there. However, my MPG is about 17 half the time, and the other it is about 11 or so.

Since the lousy(er) mileage is intermittent I finally gave up on a vacuum leak or a crack in my manifold.

I decided to pull the TB, clean and service it and the IAC valve and replace the TPS with a new Mopar unit.

I also cleaned the rubber elbow and the metal tube on the TB that feeds the MAP sensor. I might change it, too, if I keep having issues. It is cheap enough.

All these sensors are from the factory, and the TB showed no evidence of having ever been removed. The IAC housing inner hole that the plunger fits into was just nasty. The plunger on the valve was also quite grody. The TB was nasty, but only on the inside.

The PO had installed a CAI. The filter had large holes in it and burnt/melted areas that were due to leaning on hot spots in the engine bay. He obviously over oiled the thing frequently. Much of this crap seemed to be caramelized oil mixed with normal TB gunk.

We slapped the TJ back together with the cleaned and new parts. We allowed her to run rough as all get out until she warmed up and relearned how to inhale through clean bits.

Then we waited.

No CEL.

Turned her off and restarted.

No CEL.

Recently, after a code-clearing from swapping the EVAP gear, the CEL returned right after the first restart. Unfortunately, all three air codes came back and the P0123 TPS code appeared after a long time of nit having it.

So we were suspicious that it had not come back on. I was worried that it might have to do with moving in and out of idle. I did not know if you defeat the IAC merely by revving the engine for a bit while not in gear.

So we tried it anyway.

We revved it several times up to 3000 and 4000 rpm and held it at 2000 rpm for about a minute.

Turned it off.

Restarted.

No CEL.

We restarted and revved it like before about five more times.

No CEL.

However, we have not actually driven it. The codes would always reappear right after the initial start and warmup, or after the first restart. Turn it over a few times and the CEL would always return. Same codes.

Now nothing like that.

Did I finally fix this damned thing??? :pullinghair:
 

·
Detail Oriented
Joined
·
3,174 Posts
Discussion Starter · #2 ·
Let it cool off for a while (but not fully). Went out and restarted. Warmed fully. Revved and idled. Lather, rinse, repeat.

Turned it off. Restarted. No CEL.

We will drive it about 75 miles tonight.

Last year clearing the codes would work for two or three days. I worsened over time. So I will be disappointed but unsurprised if on Monday they return.

I will post back after we get home from work and take it out for some highway miles.

Thanks for reading...
 

·
Detail Oriented
Joined
·
3,174 Posts
Discussion Starter · #3 ·
Okay, got home from work. Changed. Took her out for 75 highway miles. Drove great. Too bad the CEL had come back on before I ever got out of the driveway.

P0171/P0174 -- again.

I am really frustrated.

Can anyone please post a diagram of where *all* the vacuum lines are so I can run every inch of them?

Then I need to check the manifold for cracks.

Damn.
 
1 - 3 of 3 Posts
Top