RENIX ballast resistor, TPS adjustment questions?

[xjtrailrider]

WOT numbers; ECU side 4.43, TCU side .17 or 4% (.17/4.72=.036 rounded up thats 4%)

That sound right?

 

[xjtrailrider]

Just went on a test drive and it picks up throttle like it should now, no detonation and it is not upshifting when i let off the throttle. I may have this thing fixed! I will drive it somemore before I decide wheather or not to mess with the distributer.

Thanks again!

 

[Ecomike]

WOT numbers; ECU side 4.43, TCU side .17 or 4% (.17/4.72=.036 rounded up thats 4%)

That sound right?

.17 or 4% sounds a little low at WOT on the TCU side, but I recall someone having theirs as low as 0.20 on the TCU side at WOT with no problem. As I recall mine is a lot higher at WOT on the TCU, but I have something like 4.98 volts input on mine, so mine would be higher.

So what did you change that seems to have fixed it?

Slo-Sho, what kind of mileage are you getting with those TPS settings? Mine went up about 40% with a new TPS that would calibrate to factory specs.

 

[xjtrailrider]

.17 or 4% sounds a little low at WOT on the TCU side, but I recall someone having theirs as low as 0.20 on the TCU side at WOT with no problem. As I recall mine is a lot higher at WOT on the TCU, but I have something like 4.98 volts input on mine, so mine would be higher.

So what did you change that seems to have fixed it?

The TPS settings were way off, the numbers I posted were after adjusting, sorry should have kept the old numbers but they were not close!

I don't know if the ballast resistor did anything or not and I still can't hear the pump but then again I'm running a series 40 Flowmaster so its a little throaty.

 

[xjtrailrider]

Its running pretty good since the TPS adjustment but I thought I would check the dist. indexing for kicks. With #1 TDC compression stroke I shot this pic of where the rotor is sitting compared to where #1 terminal is. The terminal location is marked by blue sharpie, as you can see the rotor is just past the #1 terminal location near the #5 terminal. I think that would make it retarded, I've run it one tooth back before and it just didn't run right.

So for kicks I put it back together and fired it up and with my Timming light with advance feature I checked the timming;
Closed loop idle-15 degrees advance
2000 rpm-36 degrees advance

I don't have a spec for the timming but does this sound correct?

I know that most engines run 8-10 degrees at idle-base. I have no way to check the base on a XJ 4.0, only the static timming and where ever the ECU puts it while running.

Any advice/opinions on the indexing of the dist. and the timming advance?

 

[Ecomike]

That is definately one tooth advanced, too far. It should be pointing directly at the blue mark where the number one wire goes. Maybe you fixed some other things like the TPS since you tried that spot. The timing light is of little help with electronic ignition. There is no spec for the 4.0 timing because it is electronic, computer controlled, from what I have read.

Its running pretty good since the TPS adjustment but I thought I would check the dist. indexing for kicks. With #1 TDC compression stroke I shot this pic of where the rotor is sitting compared to where #1 terminal is. The terminal location is marked by blue sharpie, as you can see the rotor is just past the #1 terminal location near the #5 terminal. I think that would make it retarded, I've run it one tooth back before and it just didn't run right.

So for kicks I put it back together and fired it up and with my Timming light with advance feature I checked the timming;
Closed loop idle-15 degrees advance
2000 rpm-36 degrees advance

I don't have a spec for the timming but does this sound correct?

I know that most engines run 8-10 degrees at idle-base. I have no way to check the base on a XJ 4.0, only the static timming and where ever the ECU puts it while running.

Any advice/opinions on the indexing of the dist. and the timming advance?

 

[xjtrailrider]

That is definately one tooth advanced, too far. It should be pointing directly at the blue mark where the number one wire goes. Maybe you fixed some other things like the TPS since you tried that spot. The timing light is of little help with electronic ignition. There is no spec for the 4.0 timing because it is electronic, computer controlled, from what I have read.

I'll try it, but it seems the last time I backed it up it was on the other side of the mark by almost the same diff. Maybe I just missed a tooth!

I'll give it another shot.

 

[xjtrailrider]

This time I put it dead on #1 terminal and it will not take throttle, it idles rough, misses, hesitates, stumbles, you name it. Not driveable at all!

Here is a pic of where it is set at now with #1 TDC compression stroke.

Do I need to reset the ECU?

I think when it was set last it was retarded because the rotor was past #1 terminal(the rotor rotates clockwise). And by looking at the rotor it appears to be fireing at the trailing edge. Am I thinking correct?

What if I remove the tabs on the dist. base so that I can rotate the dist. housing to fine tune it a little? The lock down clamp will still hold it in place. Has anyone done this?

I need help/answers!!!!

 

[Ecomike]

Very strange, that should have fixed it. Try disconnecting the entire battery positive cable and clamp and wires from the battery and with the ignition turned on short the detached positive cable to the ground side of the battery, that should quickly drain any capacitive memory in the Renix ECU. Then reconnect the battery and see if starts and runs, if not put the distributor back where you had it had it for now and we can all scratch our heads for a while.

If that does not work, I would suspect something is off by one distributor gear tooth in your timing chain, gears, or cam.

 

[xjtrailrider]

Very strange, that should have fixed it. Try disconnecting the entire battery positive cable and clamp and wires from the battery and with the ignition turned on short the detached positive cable to the ground side of the battery, that should quickly drain any capacitive memory in the Renix ECU. Then reconnect the battery and see if starts and runs, if not put the distributor back where you had it and we can all scratch our heads for a while.

If that does not work, I would suspect something is of by one tooth in your timing chain, gears, or cam.

I'll reset it! Do you think trimming off the tabs at the dist base and moving the housing will help fine tune the timming? I know the ECU does this but can I fool it into thinking all is well.

 

[Ecomike]

I'll reset it! Do you think trimming off the tabs at the dist base and moving the housing will help fine tune the timming? I know the ECU does this but can I fool it into thinking all is well.

Personally I would leave the tab alone, not sure what the real issues are with removing it, I know some have said they did it before. I have had Renix memory issues when I reset a TPS idle possition. They went away after about 3 shut downs and restarts, but that was idle TPS voltage memory issues. I will be real curious to see if clearing the memory solves your problem too.

 

[5-90]

Personally I would leave the tab alone, not sure what the real issues are with removing it, I know some have said they did it before. I have had Renix memory issues when I reset a TPS idle possition. They went away after about 3 shut downs and restarts, but that was idle TPS voltage memory issues. I will be real curious to see if clearing the memory solves your problem too.

I did it on my 87 - mainly as an experiment. I was able to rotate the dizzy housing 180* in either direction at idle without a stumble. If the dizzy is properly installed, the ECU will be able to handle the fine-tuning, believe me!

 

[xjtrailrider]

I reset the memory and it ran the same, rough! I dropped it back in where I had it and it runs like before I messed with it. I can live with that. There may be a issue with how the cam was degreed or it may be a RV cam and was degreed as a stock grind, don't know. I know that I speced a stock grind on the build sheet.

I have a extra dist. so I just tried it anyway. I dropped the modified dist. in on the original setting and then tried to play with it by moving it a few degrees either way, ran the same no matter where I put it! I'm leaving well enough alone but if anyone wants to see how I modded the dist. here are some photo's.

Thanks for everyones help! I'll drive it and be happy with it the way it is!

 

[Shorty]

Its running pretty good since the TPS adjustment but I thought I would check the dist. indexing for kicks. With #1 TDC compression stroke I shot this pic of where the rotor is sitting compared to where #1 terminal is. The terminal location is marked by blue sharpie, as you can see the rotor is just past the #1 terminal location near the #5 terminal. I think that would make it retarded, I've run it one tooth back before and it just didn't run right.

So for kicks I put it back together and fired it up and with my Timming light with advance feature I checked the timming;
Closed loop idle-15 degrees advance
2000 rpm-36 degrees advance

I don't have a spec for the timming but does this sound correct?

I know that most engines run 8-10 degrees at idle-base. I have no way to check the base on a XJ 4.0, only the static timming and where ever the ECU puts it while running.

Any advice/opinions on the indexing of the dist. and the timming advance?

as the rotor turns, it's gonna fire when it reaches the terminal which would actually be before the engine reaches TDC. As pictured, the ignition timing is advanced-- not retarded.

 

[xjtrailrider]

as the rotor turns, it's gonna fire when it reaches the terminal which would actually be before the engine reaches TDC. As pictured, the ignition timing is advanced-- not retarded.

OK, I guess I'm the retarded one! lol!

Thanks for the info. It seems to run much better now even in our single digit lows at 5am it ran like a champ to work. Better than ever. The TPS adjustment is working. It will now lock up in 3rd, it didn't do that before, and it will hold OD down to 25 on steady throttle and will pull back out in OD if you feather it up. It would not even touch OD below 45 before and would never lock up in 3rd unless you had the shifter in 3rd. I like this much better!

 

[Ecomike]

OK, I guess I'm the retarded one! lol!

I've always liked to think of myself as advanced!:yelclap:

 

[5-90]

I've always liked to think of myself as advanced!:yelclap:

Now there's a minority opinion... (Just kiddin'. Nothin' but love for ya, ya know...)

RENIX timing is a funny creature. I had access to an MT2500 some years ago, and was checking the timing in realtime. I was mildly surprised that the engine was running as well as it was - but run it damn sure did! Timing didn't change too much with fuel octane, either, so it wasn't caused by detonation and knock.

Why do you think I'm trying to sort out the whole system?

 

[xjtrailrider]

Its still running better but I've only put 60 miles on it since doing the work so it may take a few more miles to see if the ECU re-learns and does something funny.

The amazing thing is the shifting! I never went from 3 to 3 lock-up and then to overdrive, let alone under 40 mph. Gas mileage should improve. Also has much better acceleration and so far no detonation. Idle is still low but much smoother. I probably jinxed it but I'll hold out hope!

 

[Slo-Sho]

From the pic of your rotor the ECU isn't taking advantage of the full length of the rotor. If you are using the stock crank positioning sensor do this;
Set the crank pulley to 12 degrees before top dead center and adjust the distributor so that the number one terminal on the cap is directly in the middle of the rotor. This will get your fuel sync and ecu timing control more accurate.

 

[xjtrailrider]

From the pic of your rotor the ECU isn't taking advantage of the full length of the rotor. If you are using the stock crank positioning sensor do this;
Set the crank pulley to 12 degrees before top dead center and adjust the distributor so that the number one terminal on the cap is directly in the middle of the rotor. This will get your fuel sync and ecu timing control more accurate.

Thanks Slo-Sho, I picked up on that too and adjusted the moded dist to compensate except at 8 degrees as said. I shoulda posted that info on my last post. Thats were I left the dist. set at Tuesday evening. Shoulda took a pic! I advanced the pulley as said but to around 8 degrees and centered the rotor on #1 terminal. I can try 12 it would be no problem.

I don't know what helped the most, the TPS, ballast resister delete, or the dist movement, due to the fact I broke one of my old drag racing rules, to only adjust one thing at a time, then run it!

But regardless it is running real nice right now, sounds different as well. And like I said I can run OD down to 25 or so then pull it back up with soft throttle with no kick back to 3. It accelerates hard when i want it to, seems more responsive. No issues with driveability at all. It doesn't have that rich smell to it either any more. It feels as strong as my 00' right now.