little renix help (give a little gas good...give it moderate and its dead)

okay...88' 4.0/ba-10/231

i get a surging when i start up cold (no high idle, right to 750 or so...then drop to 500...maybe 400 and back up, down and back up. but it drives just fine if you give it a little gas.

however when you go and get on it a bit....it has a dead spot where its laughs at you.

my friend drove it tonight and he said is seems like it's missing almost when you get on it (no stutter though)

so heres the things when you are drive easy (maybee 1/8-1/4 throttle its fine...drives and accelerates decent...get on it and its like nothing is hapening...like hte xj is dead almost...no pick up at all.

any help is appreciated...i thinks is the engine temp sensor (screwing with the injector timming), but i'm not sure because of hte throtle part of this equation...i think it might be the tps all fucked up (cleaned the tb with the sensor in, didn't know it was a no no)...i guess i can unplug that and see if its that.

then again it could be a vacume leak (but all seems ok).

the cap/rotor are new, wires are new, plugs look new.

and help is appreciated...thanks

In no particular order...

Check/change the TPS. They can develop flat spots (I've had to deal with this before...) and cause problems like that.
Retorque your manifold screws - 21 pound-feet. They can loosen, causing a vacuum leak, and cause a "wandering idle.
Check your CCV lines. I posted NAPA part numbers several months ago when I got them, and the full set runs about $50. They'll also age, crack, and leak.

Try this - see if you can't rev up your engine past the flat spot, and see if you don't get smooth throttle action again. A "flat spot" is usually fairly small, and you can pass it...

5-90

Clean the TPS with electrical contact cleaner (NAPA sells it. Similar to the old tuner cleaner for rotary dial TVs of years ago) and ALL underhood connectors (and being 88/87, then there is a BIG one above the brake booster that causes issues) I even take apart the bulkhead connector and clean it out.

Concur on taking apart the bulkhead connector (the infamous C101...) and repacking it with Ox-Gard (just a bit...) but I wouldn't bother cleaning out the TPS. Just replace the thing - it's getting old.

The way it works is that there is a wiper arm and a carbon track inside there - the carbon track will gradually wear away as the wiper arm moves across it. Also, when you run at a specific "part throttle" for a while (like cruise...) you'll develop a "flat spot" in the sensor - the carbon track gets compressed under the wiper arm end, and the resistance of the thing changes from the curve the ECU will expect. Cleaning don't fix it.

Just pop for another one, install, and adjust per FSM. It will be a LOT easier! I'd also clean the throttle body while you're about it - do it after you take the old TPS off, but before you put the new one on.

5-90

would that contribute to poor gas milage?

thanks

Vacuum leaks would. The TPS less so, but anything that affects effective engine management will have a negative impact upon efficiency...

5-90

Check the vacuum hose going to the MAP sensor. Every time I tune up a Renix (or HO come to think of it) I clean the vacuum hoses out (LOTS of crud comes out of the MAP sensor one on high milers)
A can of BG's 44K (available at most NAPA stores. And yes, 44K is the part number) should clean up the crappy gas mileage. Your EGR may be sticking too. (or hooked up wrong) Engine coolant temp sensor (one for the EFI that is on the side of the block and NOT the knock sensor or for the gauge) may be bad and going to 1/2 way only (there is a short changeover point that it goes between cold and hot where they can stick when they go bad) and putting the computer into "limp" mode, but not throw an error code.