Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of JUNE's Ride of the Month Challenge!

1 - 16 of 16 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter · #1 ·
What provides power to the distributor and the tach???

Have a 91 4.0L auto with 38K miles. After it gets warm it stalls. Sometimes it restart right away, like .2 seconds later by itself, sometimes the next time you crank it, and sometimes is takes about a minute.

But it always restarts, and restarts strong.

Lately I noticed the the tach reads 0 when it stalls, even though the Heep my be doing 60.

I'm thinking was is stopping power to the distributor is also affecting the tach. So . . .what does that?
 

·
Drives by Braille
Joined
·
13,642 Posts
Well the tach reads the rotations of the distrbutor, and if the morot stall, the tach will drop to zero. I don't if they have a pick-up coil in the distributor, but if its going bad it will cause the motor to cut out... or an ignition control modual will do the same.
 

·
Registered
Joined
·
227 Posts
What provides power to the distributor and the tach???

Have a 91 4.0L auto with 38K miles. After it gets warm it stalls. Sometimes it restart right away, like .2 seconds later by itself, sometimes the next time you crank it, and sometimes is takes about a minute.

But it always restarts, and restarts strong.

Lately I noticed the the tach reads 0 when it stalls, even though the Heep my be doing 60.

I'm thinking was is stopping power to the distributor is also affecting the tach. So . . .what does that?
I have electronic ignition in my 89 YJ, I installed it myself. The unit is powered off a switched circuit and the tach is run off the distributor. When the ignition module starts acting up, it will usually start failing to start after a short drive but will start strong after you let it sit for a few minutes. Then one day it won't start at all. The module is an inexpensive unit and is well worth changing out.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #4 ·
Is this the case with FI motors too? I have asked for an ignition module from part stores before, but they don't have it. They usually have a ignition coil. I tested my coil and it's within spec.
 

·
Registered
Joined
·
4,241 Posts
I just put an ignition control module in my 87 a couple months ago. I got the part at Advance Auto Parts for about $30...I can't remember exactly how much.
 

·
Registered
Joined
·
592 Posts
I swapped in a 98 4.0 on my 89YJ and wired it so I can tell you there is not an ignition module that is used with the 4.0 engine.

Have you pulled the codes on it yet?
Do you know how to pull codes?
These sometimes will tell you if a sensor is going bad.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #7 ·
The only codes I get are the "You disconnected the battery lately", and 33 (I think). Whatever the A/C one is. I have A/C that works, have no A/C relay. Thats all the codes I get. Early when this happened I got the Crankshaft Position sensor code, swapped that out, still stalled.
 

·
Registered
Joined
·
592 Posts
The bad news is that if it was a sensor it should show up in the codes when it stalls. The first thing that will show a weak ECM is heat and it will not show a code for that as the computer is the problem. Do you have someone that lives close to you with a jeep of about the same year? Swap the ECM and see if the problem goes away.
It is not a good suggestion but the cheapest one I have at this point:D
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #9 ·
I guess I'll have to find someone. The problem that I have is that the problem is so intermittent. Last time it was four days between stalls. I've driven it for almost a week with no issues. Did I fix it? Maybe I'll find out today.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #10 ·
how dumb is it to spray the ECM with water? If its a heat issue, and if I can get it to present, and then cool down the ECM, and the problem goes away, then I figured it out. Right?
 

·
Registered
Joined
·
592 Posts
I talked to Joe at Absolute Offroad today he suggested that the Crank Shaft position sensor is going out. It will not throw a code as once it starts the sensor is fine.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #12 ·
I replaced that sensor 3 weeks ago after one of the stalls gave me that code. the only codes I get now are 12 and 33. Do you think I got a semi bad sensor from Pep Boys. (I loathe PB)
 

·
Registered
Joined
·
592 Posts
I do not buy from Checker, AutoZone, or Pep Boys. I buy Napa or Car Quest. The part could be bad as it has happened before at this point is only a best guess. Sorry i could not be of more help:confused:
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #14 ·
Unfortunately, the ECM seems to make the most sense to me. I'm going to fab a heat shield mounted with some windshield sprayers over the ECM. If the Heep takes longer to stall, and then once cooled by the mist will go longer without stalling again, I know I'll be on the right track.
 

·
Registered
Joined
·
21 Posts
Discussion Starter · #15 ·
On wrong track.

Still stalls. Now have error code 14. A MAP sensor thats 3 weeks old, I wouldn't think a bad MAP would make motor stall.

Today it did run longer in Neutral, and would stall when put in gear.

Going to test conductivity of wiring harness, see if there is a break I can find. Anyone know where in the ECM plug the MAP wires are?
 
1 - 16 of 16 Posts
Top