Ignition control module???

[Infidel Edition]

Hey,
I had the starting issues and swapped out the CPS (PITA but done). :bacondance:

I had hoped that it was the culprit of my slow starting (not to mention the 2 or 3 no starts). :pray:

I haven't had issues starting in the few times I've drivin' it since. But I did come across another theory as to what my starting issues were
......... the Ignition Control Module.

I still have an occasional high idle (~ 1200 to 1300 range), but not as much as before I swapped the CPS.
And it does start, but it still seems a bit slow given that I just did the big 3 upgrade on bat / cables / alternator.

:timeout: So in skimming various posts, I came across a link to a link that took me to a site that seemed to believe my issues (though in someone else's jeep) were due to the ICM vs. the CPS.

Is there a way to get that tested before I drop the $$$ to replace it?
ie. would that show up on a scanner?
or is there a voltage reading?
...if I can find someone with a scanner that will read RENIX...

I'm running at the moment, but I'm about to take a 1000 mi. trip for military :patriot: and need to know it's gonna start when I turn the key.
Tomorrow or Wed. I was going to pull the ICM and ECU and use a brass brush to clean all connections / as well as sand all grounds I come across.

Thoughts?

[F1Addict]

Forget codes on a Renix. Verifying good grounds (a known issue from the factory) is a good starting point. Pay close attention to the grounding post on the dipstick. Cleaning the ICM contacts and smearing them with dielectric grease is also a good idea. However, your problem sounds to me like a vacuum leak. First place to check is the line leading to your MAP sensor, then all the rest.

[Infidel Edition]

Forget codes on a Renix. Verifying good grounds (a known issue from the factory) is a good starting point. Pay close attention to the grounding post on the dipstick. Cleaning the ICM contacts and smearing them with dielectric grease is also a good idea. However, your problem sounds to me like a vacuum leak. First place to check is the line leading to your MAP sensor, then all the rest.

I have a friend (well, I know a guy) that picked up a ICM and coil, but never used it as he rolled his jeep. And replaced with a 93 ~ which incorporated them into his ECU. So, he'll cut me a deal on the set (under $100).

My goal is to figure out how to remove as much vacuum as I can -- if not all of it. There's gotta be 5 miles of vacuum line in there!

[89Laredo]

Its normal for a renix to take ~5 sec to start.
High idle is usually caused by vacuum leaks.

[Infidel Edition]

Its normal for a renix to take ~5 sec to start.
High idle is usually caused by vacuum leaks.

*It used to start quicker ~ then slowly till it didn't start those couple times. I swapped the CPS, and it starts, but in the slower range. That's the main reason I was thinking something electrical.

Otherwise, it generally idles around 800 till it gets warm. Then 'sometimes' 1200 - 1300. ~ other times at 900 - 1000.
** Occasionally even as high as 2000 +/-.

At first, I thought it was a sticky go peddle and would pump it a time or two. This lowered the idle on occasion. And I've pulled the throttle body apart and cleaned it with no real change.

A time or two, I've cut the engine because of the high idle and restarted it. This has resolved the issue more often than not.
...and once or twice, restarting it didn't resolve the issue. ** those times I've drivin it down the road and it'll fix itself eventually.

I've done the spray on the vacuum lines to check and haven't found anything.

There is a Thermal Check Valve on most vacuum diagrams. But it's part of the air filter assembly (or appears to be on the diagrams).
Being thermal, it is implied that it kicks in when the temp changes. Could that be where the issue is?

[89Laredo]

Almost sounds like your iac is acting up... it can get sticky, soak it in carb cleaner and spray it out good with air.

There is a vacuum activated shutter on the "snout" of the airbox.

The intake/exhaust bolts can loosen over time and cause an intermittent leak before they get real bad.

The coil/icm are potted and solid state, they almost never go bad. Cleaning the contacts isn't a bad idea.

[Infidel Edition]

Thanks for the input. It gives me direction

Cleaning is free (or close to free)
...so is checking bolts to make sure they're tight.

I'll try that first and see what she does.

[ParadiseXJ]

IMHO

Don't "eliminate" vacuum lines unless you know exactly which lines (and what they do) you are removing. I see guys that have torn out their vac lines thinking they'd get better mileage etc. only to complain later than things aren't working right.

As per usual my advice is to replace (as opposed to repair with tape) any vac line that is even suspect.

Just my 2 cents

I've had 2 Renix Jeeps and never had a single problem with ICM after a collective 455K miles...I cannot sat the same for vacuum related problems

[Infidel Edition]

Not pulling lines for power (ie. the Nutter thing)...
Rather, I was looking at moving the canister from the bumper and looking at what it serves.
From what I gather, it's tied to the axle disco, cruise control, and HVAC.
~ as my front disco is locked in and the cruise control is DOA... it should only be tied to the HVAC.
So, in theory, I could replace it with a smaller canister ('95 grand) with fewer connection points (3 vs. 4) and just run the HVAC. AND remove the cruise lines and the disco lines.
~ just thinking about it / haven't fully done it.

The engine / emissions (from what I gather off the Mitchel manual) are tied to the canister by the firewall under the radiator fluid res.
** Those, I'd leave alone as I have to still pass DEQ.

Main goal is to simplify the clutter...:rolleye0012:

[ParadiseXJ]

AFAIK, the vac ball, football, whatever, only runs the HVAC and cruise. The source off the manifold, then to the servos to the cruise, and then the blend doors. The axle disco has it's own source directly from the engine and is harnessed from t-case to axle to vac switch.

I know this because I've operated the disco axle with out the reservoir even hooked up. If you look at the ball, there's one port labeled "vac" or "vacuum" which is the source line, the unmarked hole goes to the servo. My MJ has no servo line to the cruise, since I don't have cruise. My reservoir only has the one outlet and it only goes to the HVAC. The "football" reservoir has (on my XJ) two "source" lines and two servo lines. One to the cruise and one to the HVAC. That's it.

The disco runs off the red/green/yellow/blue vac lines.

I think I went off topic here...just sharing MY experience.

[4.3LXJ]

On mine, everything was hooked into the line to the reservoir

[ParadiseXJ]

OK, now I'm confused.

My ball is relocated into the engine bay, but all I did was shorten the two (2) hoses. Nothing else was hooked to the ball, yet everything worked.

I'll watch and learn...and look at my sons XJ. I can't look at mine with any certainty because I locked over the disco, swapped my NP231AMC (88) to a NP231J (94) when I swapped trannys and eliminated all the vac lines to and from the t-case, I just don't remember removing anything from the servo line. My son still has a working disco axle on the 90.

EDIT: But even if the vac ball is attached inline to the disco, it still has little or nothing to do with the engine (emissions) side of the vacuum system. The only thing in common there is the vac line source off the intake manifold.

[Infidel Edition]

cleaned the tps...

I noticed it's really caroded and pry needs to be replaced in the near future.

I was able to adjust it too a good idle. but I'm not sure it'll last