RENIX Issues (Hesitation, high idle, poor fuel economy)

I've been working at getting my RENIX truck running better for a few months now, and I've made progress, but I still have a number of issues that I'd like to correct. I'm figuring that they are all inter-related, and I'd like to see if anyone has any insight. It's an '89 XJ Limited with an AW4.

Symptoms:

* Truck revs to ~2500 upon cold start, and stays there for ~60 seconds. If I put the truck into gear, it obviously tries to take off as if the accelerator is stuck.

*Occasional high idle. Every once in a while, the truck will idle at ~1200rpm when in Drive, and at 2000+ in Neutral or Park. Shutting the truck off and turning it back on usually corrects this.

*Truck hesitates below 3000rpm like it's not fueling properly, then takes off at 3000 like it snapped the chain holding it back.

*Poor fuel economy. I'm averaging 11-14mpg. That can't be right.

* Off-idle hesitation. This is the most annoying issue of them all. At throttle tip-in, the truck tries to stall(and often succeeds). This makes parking lot maneuvers and stop-and-go traffic VERY difficult. Having to gun it every time I want to get the truck moving is, to me, not an acceptable way to deal with it. I have almost run into other vehicles in parking lots on a number of occasions because of this, and I don't want to think about how much this problem is going to suck if I try to use the truck for any type of 'wheeling. I absolutely have to correct this issue.


Any thoughts, suggestions, experiences are greatly appreciated. This stuff is driving me nuts!:gonnablow

tps may be bad or not adjusted proporly. aslo clean the throttle body and IAC

check for vacuum leaks and intake exhaust manifold leaks.

do a search for tps adjustment.

tps may be bad or not adjusted proporly. aslo clean the throttle body and IAC

check for vacuum leaks and intake exhaust manifold leaks.

do a search for tps adjustment.

may also need a new o2 sensor

have you replaced or at least adjusted your throttle position sensor?

Throttle body and IAC have been cleaned, and the electrical connectioins for them(and many other components) have been cleaned and dielectric greased. I noticed a bit of an improvement when I cleaned up the relays and the relay mounting block on the passenger's side of the engine bay.

Any simple instructions for adjusting the TPS?

its in here somewhere i believe

http://www.naxja.org/forum/showthread.php?t=905849&highlight=renix+files

maalox said:

Throttle body and IAC have been cleaned, and the electrical connectioins for them(and many other components) have been cleaned and dielectric greased. I noticed a bit of an improvement when I cleaned up the relays and the relay mounting block on the passenger's side of the engine bay.

Any simple instructions for adjusting the TPS?

Click to expand...

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

Ok, adjusted the TPS today per the instructions I found at http://autorepair.about.com/library/faqs/bl232i.htm . Here are my findings/results:

Starting output voltage 3.93
Starting input voltage 4.71
Starting ratio: .834

So it was at the high range of the spectrum (0.825-0.835). After a few adjustments, I got to these readings:

Finish output voltage 3.91
Finish input voltage 4.71
Finish ratio: 0.830

I found that tightening the screws is enough to throw it off 0.002-0.003, so I would reccommend leaving the multimeter attached while yout tighen the screws, or check it again after you've tightened them.

Results:
The off-idle hesitation is better, but still not perfect. I may try to adjust it into the lower end of the spectrum(0.825) to see if that helps. I won't know until later if the hesitation below 3000rpm is gone, and I'll find out tomorrow morning what the story is with the cold start high idle.