I have a 1987 YJ with a 4.2 my son and I were working on it and inadvertantly left teh key on and ran down the battery. I put the charger on it and set the timer and left the shop, the timer did not time down and it charged for about 30 hours. This melted the ignition module but before I found and replaced that I put in a new pick up in the distributor, plugs, plug wires, coil, rotor and cap. While I had the distributor out replacing the pickup I got the motor out of time. I have timed the motor with a timing light and am certain it is in time. Now it will start and idle and sound ok but the longer it runs the worse it gets it mill start to miss and then die. It will even backfire through the carb and tailpipe as if it was still out of time. It was running just fine before the charger mishap...any suggestions?
1987 yj 4.2
- Thread starter tipsi2
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defmornahan
New member
Only thing I can think of is that the computer is senile. Has this relic (I've got an '87 too...) had a Nutter bypass done?
87SixInlineYJ
New member
I have been reading about this Nutter bypass. Is this a needed upgrade for the 87? It seems to me that if someone upgrades all the modifiable parts in the engine bay to performance grade items that it should be fine, no?
Regarding the timing, yea your gonna have to swap out the battery(try an optima yellow top), and adjust the timing.
Regarding the timing, yea your gonna have to swap out the battery(try an optima yellow top), and adjust the timing.
defmornahan
New member
A Nutter bypass cuts the computer out of the loop so that it can't adjust the ignition timing. If you search on "Nutter bypass" you'll find quite a few descriptions of the procedure. It's just cutting two wires (purple and orange, should be) from the computer (the place in the middle of the firewall where all the wires feed in, as opposed to the spot by the driver's side) and splicing them straight to the ignition module. Older Jeeps had that configuration stock.
I've actually read that many items (e.g., an aftermarket carburetor; I have a Weber) practically REQUIRE the Nutter to also be done. I have done it and frankly didn't notice any difference before to after, but that may just mean that my computer wasn't in as bad a shape as some people's, plus my ignition module was sickly and my fuel pump didn't have a filter and was passing some fairly dirty gas. I've read several comments on threads where people expressed amazement at the improvement.
One other random thought...you did time it with the distributor vacuum hose disconnected and plugged, right? I'm just asking because I've screwed that up twice myself. Also, did you time it with the pedal at idle or did you time it at 1600 rpm like the label says? I'm not sure which is right, but if you did one try the other. I still think the computer may be your problem.
I've actually read that many items (e.g., an aftermarket carburetor; I have a Weber) practically REQUIRE the Nutter to also be done. I have done it and frankly didn't notice any difference before to after, but that may just mean that my computer wasn't in as bad a shape as some people's, plus my ignition module was sickly and my fuel pump didn't have a filter and was passing some fairly dirty gas. I've read several comments on threads where people expressed amazement at the improvement.
One other random thought...you did time it with the distributor vacuum hose disconnected and plugged, right? I'm just asking because I've screwed that up twice myself. Also, did you time it with the pedal at idle or did you time it at 1600 rpm like the label says? I'm not sure which is right, but if you did one try the other. I still think the computer may be your problem.
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