yet another renix stalling issue (this one more complicated)

[tealcherokee]

over the past week i swapped in a 4.5L stroker built off a HO motor into my 88 jeep

drove fine the first few days, not i have a VERY weird stallin issue

for starters, the jeep has no exhaust as of right now, and it is running rich, but not terribly rich. I have the 88 fuel rail on it, 39psi FPR, HO throttle body, used the 96 TPS (cut and spliced the connectors) but its only putting out 3.55v at WOT (i have a new TPS going on soon). I check the CKP, its good, CMP has a high altitude setting, i dont know which it was on, it was running so i left it. the motor is a 4.5L 9.8:1 compression 260/272 crane cam.

When adapting i moved the temp sensor from the renix block, to the HO tstat housing, i also put one in the radiator, and one in the back of the head.

Now, the issue, when the jeep is cold, it seems to drive fine. I just drove to the gas station, no issues, shut the jeep off, when i got back outside it wouldnt start (just went in for food), waited a few min and it started up. got about 200 feet up the road, stalled, waited, and it started (if i dont wait it just cranks). it probably stalled 4 times on the less than a mile ride home.

when it stalls, the tach instantly drops to zero, even tho i was probably doing 30mph and it was still in drive. this leads me to think its the body to block ground, but its clean and tight, so are all the other grounds on the block.

As of right now like i said theres no o2 sensor, also no knock sensor, both will be hooked up tmrw, and neither should cause this type of intermetint issue

IIRC, the renix jeep can run with out the CMP so i think im going to try with out it to see if that high altitude thing can be causing an issue.

Ive been reading the other threads about renix issues, but this is just baffling me

thanks in advance

[CRASH]

The Renix system requires the MAP, the MAT and the CPS to run.

What is a CMP?

[tealcherokee]

cmp is the actual abbrv for cam shaft pos

[5-90]

Also called the SYNC.

RENIX should run without it, but not as well, because the computer has to "guess" when #1 is coming up to fire. The SYNC sensor is used to "order" the signal from the CPS, mainly by letting the ECU know which three cylinders are coming up (the SYNC pulses once per revolution of the distributor - meaning that it essentially tells the ECU which revolution the crank is on. The crank spins twice per spin of the cam/distributor.)

The tach is driven by the ignition - if there are no ignition pluses, there is no signal to drive the tach. Sounds like you've still got RENIX ignition installed - try this:

With the engine OFF, get a hair dryer and heat up the ignition module/coil assembly. Five minutes should do it.

Once the ignition is noticeably warm to the touch (but everything else should still be COLD,) try to start it.

I've lost a couple ignition modules that were going intermittently due to heat-related failures, and that was how I isolated it.

5-90

[87manche]

when the ECU senses the motor is warm it goes into closed loop mode. Since you have pinpointed it to a warm motor problem thenthat's my guess. As soon as the RENIX ECU tries to go closed loop it probably freaks because there's no O2 sensor attached.
That's my theory anyway.

[tealcherokee]

hmmmmm, intresting theory about the coil, ill have to try that tmrw

not sure if im buyin the o2 thing, because they use a heated o2, so the o2 should close the loop with in 30 seconds

[5-90]

Originally Posted by tealcherokee

hmmmmm, intresting theory about the coil, ill have to try that tmrw

not sure if im buyin the o2 thing, because they use a heated o2, so the o2 should close the loop with in 30 seconds

That's about the same thing I was thinking - if it were an "Open/Closed" loop problem, you should see it a lot sooner.

Ignition modules in general can be a little shonky when they start to go out, and you'll generally notice it when the MODULE gets warm - that's why the hair dryer. Focussed heat (upon the module/coil) will help to highlight if you're having module trouble, and you can move forward from there, whatever the result.

5-90

[tealcherokee]

well out of stubborness i changed the engine ground and added a body ground, dont think itll help, but i cant try till tmrw due to the open header

[tealcherokee]

anyone know what this connector is, and if this temp sensor is ok here?

[old_man]

That looks like the connector for the A/C low pressure switch mounted on the dryer.

[tealcherokee]

very possible, considering i removed my AC

[tealcherokee]

i think im going to throw a coil at it tmrw, any reson why right after the stroker the coil would go, or just bad luck? would it be worth my time/possible to put the HO coil on it?

[CRASH]

Originally Posted by tealcherokee

cmp is the actual abbrv for cam shaft pos

Oh, on a Renix, I know it as the SYNC.

[87manche]

Originally Posted by 5-90

That's about the same thing I was thinking - if it were an "Open/Closed" loop problem, you should see it a lot sooner.

5-90

I was under the impression that the ECU ignored the O2 sensor until the motor was warm.
Looks like I gotta go read the Renix book again.

[xjbubba]

Pretty difficult to trouble shoot stalling issues with half of the required sensors missing. The knock sensor's input, or lack thereof will cause timing issues, and of course the absence of O2 readings to the ECM will cause fuel delivery issues. Generally, closed loop is obtained when the engine temp is above ~150* and the output of the O2 sensor is going above and below the theoretical optimal fuel/air mixture point--in other words--appropriate cross counts detected by the ECM. No O2 sensor, no closed loop. Period.
The ECM supplies ~5vdc to the TPS, so at WOT you should see ~4.8vdc. So there seems to be a problem there. What is the reading in the idle position? You should see ~.8vdc.
Oh, and the O2 heater is under ECM control. It's only used below prescribed engine rpm and MAP output. The assumption is that above the specified RPM, the exhaust gas will keep the O2 sensor hot enough to operate.