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renix won't rev

S

shawnxj

NAXJA Forum User
Location
portland, tx
built a stroker motor for my renix. starts up and idles just fine but wouldn't rev over 3000 rpm in park or driving around. replaced the cam sensor cause it was the only sensor i couldn't test since i don't have an analog meter. started it up and now it won't rev past 2500 rpm. figured i'd replace the cps as well since it was old and probably wasn't reading right under higher rpm. tested fine at idle but didn't check it any higher. well that knocked my rev limiter down to 2200 rpm

idle quality is as perfect as gets. i've moved the distributor 1 tooth back and it starts running really rough. guess i could move it 1 tooth forward and see what it does but it would put the rotor at 6 o-clock which would be too far forward.

tomorrow i'm going to put the old distributor back in and leave the new cps in and see what it does. might move 1 tooth forward as well. any other advise or help would be appreciated
 
Forget that idea, you have pretty well eliminated that posibilty. Sounds like either a poor ground on the TPS, or a bad TPS that does not go high enough in voltage output at WOT.

Have you tested the TPS ground on the ECU side of the TPS? It should be less than 1 ohm to the battery negative post. At WOT the TPS output voltage should be about 87% (IIRC, or 83%) of the input voltage from the ECU which should be 5 volts (about 4.8 to 5.1 is OK). So if you have say 3.8 V or lesson the output side instead of about 4.6 volts at WOT it is the TPS.

Sounds like the TPS so far.

Pretty sure it is the TPS sensor ground is poor or the TPS has gone bad.
 
replaced the tps and set it according to cruiser's instructions. never did check the wot measurement though. i'll check the ground as well but i made big beefy ground cables when i put in the new engine
 
Renix TPS can fail about 6 different ways. So it is probably the WOT problem. I had one drove me nuts, turned me into a Renix TPS expert by the time I was done figuring it out on my own, LOL ( see "The RenX Files thread here). It was the TCU side of the TPS doing the weird stuff making mine up shift at 1200 rpm, I was shifted into 4th gear (AW4 auto) by 20 mph at WOT , LOL. Took 4 minutes at WOT to reach 60 mph!!!!:scared:
 
If I am wrong, I would check the TPS WOT voltage at the ECU!!!

What year is it? C-101 ?

Is the dizzy new? Or is it old and worn on the shaft bearing?
 
mike it's a brand new distributor. cost the same as just the cam sensor and i didn't have to take it apart so i bought a new 1

it's an 88

cruiser i didn't scrape the paint off the block but the computer grounds are sitting right on top of a brand new #4 ground wire going straight to the battery
 
hey while i have both of y'alls attention. i have a 3 wire plug with only 2 wires in it coming out of the injector harness. what's it for? every sensor i can think of is accounted for. map, crank,cam,tps,iat,o2,knock,engine temp, iac all connected
 
tps scales just fine and wot is a little high at 4.62 but i have over 4 ohms to ground so i guess i need to start trancing grounds
 
Last edited:
added a jumper from the tps ground to the battery and now it idles really high(hits the 2200 rpm rev limit i currently have) but still hasn't done anything to help the problem....
 
Any chance you are off a little with the distributor?
 
ok i have .9 ohms with the key off, 97.6 ohms with the key on and 30 ohms with the engine running. how many grounds is this thing supposed to have? i have 3 at the dipstick and that's it. the ground on the firewall has nothing but the jumper going to the dipstick
 
went through all the grounds like and redid them according to cruiser's blog or whatever you'd call it and got the ohm's down to .05 with the key off, 80 ohm's with the key on and 10 ohm's running. checked the cps and it was only giving me .220 volts so i put the old cps in and i'm back to being able to rev to 3000rpm again but now the idle quality is crap like the cam sensor is reading wrong or i'm a tooth off so i'm going to put the old distributor in and see what happens
 
my rotor is pointed exactly like that 1

driveability is fine except it still won't rev. shifts fine pulls like a stroker should. had it up to 70 with no issues about an hour ago. i'm starting to think the ecm just can't handle the new motor

installed the old distributor and went 1 tooth forward and 1 tooth back. forward wouldn't start 1 tooth back ran like shit. right now it's set dead on like that picture. idle is fine for about 20 seconds then it drops down to around 400 and it likes to try and die at stop lights. tps is set to .80 volts with a 4.82 input voltage
 
shawnxj said:
my rotor is pointed exactly like that 1

driveability is fine except it still won't rev. shifts fine pulls like a stroker should. had it up to 70 with no issues about an hour ago. i'm starting to think the ecm just can't handle the new motor

installed the old distributor and went 1 tooth forward and 1 tooth back. forward wouldn't start 1 tooth back ran like shit. right now it's set dead on like that picture. idle is fine for about 20 seconds then it drops down to around 400 and it likes to try and die at stop lights. tps is set to .80 volts with a 4.82 input voltage
Click to expand...

OK, time to tell us about the stroker!!!! Headers? Cam? and Injectors? What injectors, and flow rate are they???

We may need a stroker-Renix expert, which I am not!!! But I do know of a resent issue where a guy used larger flow injectors on a 4.0 and he had running issues like yours as the Renix ECU could not handle. He is in Hawaii, and I think Mu-a-dib had issues with his last year. Cruiser, are you still working on a stroker, or running one?
 
cruiser54 said:
That is NOT a cam sensor BTW. The Jeep will run just fine without it plugged in.

Always check the sensor grounds with the key OFF.

Go here and read along with viewing the photo in post 13
http://www.cherokeeforum.com/f51/cruiser54s-mostly-renix-tips-153657/
Click to expand...

Exactly!!! With the power on, there is power running through the ground wires, and back voltage, tiny as it may be, will show up as higher resistance on an ohm meter, and can damage the meter.....Always do ohm test with the vehicle power off.
 
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