comanche1989

If someone has more knowledge of the inner workings of distributors and why it happened, I would be interested to hear and learn about it!

As far as I understand, it was a mechanical issue causing an electrical issue. The distributor was worn out, causing oscillations effecting both the Cam position sensor ( I know the Jeep can run with it unplugged) and the rotor. I believe once the engine reached a certain rpm, it created an almost death wobble effect, where it oscillated at that certain rpm range. Certainly a strange problem.

An update just incase people have a similar problem and are searching the forum. My distributor itself was bad. Now that the distributor is replaced (as well as nearly every sensor and ignition component) the Comanche is running smooth as can be!

I just went and bought a new MAP and installed it. No change at all in issues, still behaving the same.

When I unplugged the TPS, it idled fine but when I pressed the gas it would stall.

MAP vacuum source is the closest nipple on the H.O. Intake. I’m fairly certain the location is not an issue, as I have put 10,000 or so miles on the engine since I put it in. Should I go ahead and spring the money for a new MAP? I hate throwing parts at a problem. The voltage swings up as the butterfly is opened.

EGR was deleted when I when to a H.O. motor. I have done most of the renix tips. I will however double check all wires. They are fairly new. How would I set .83 for a closed throttle position when I can not get the TPS to clock any more? Adjust the idle set screw? I will be buying a new MAP sensor come payday to swap in.

Just took another look at my truck. Found about 2 ohms of resistance between back-probed TPS and negative battery terminal. Re-cleaned the dipstick ground thoroughly and that reduced resistance to the point where my cheap multimeter is not reading any. This brought my voltage on the TPS when adjusting up to .81 v. My voltage I need to be able to adjust to is .83v. Is that much of a difference negligible, or will it cause my issue? I can not clock the TPS any more. Line between manifold and MAP is in good condition. Is the MAP sensor responsible for fuel/air mixture along with the 02 sensor? If I remember correctly backfiring means that the mix is too lean.

Catalytic converter was gutted by PO. H.O. throttle body. I will check MAP vacuum line in a few minutes. I will keep everyone updated.

It is an 89 TPS with the HO throttle body. Adapted using the method in the link.

Thanks for the replies. My TPS voltage from back-probing was 4.87. From what I understand this is within a reasonable limit. I have not adjusted the Idle Set Screw, however the butterfly opens and closes no problem. Is there a procedure for testing the MAP sensor? I don't recall seeing one. When it comes to the CPS, I have not had any issues when no start at all. However, I will test it when I have a chance. To me it seems like a fuel issue, due to the backfiring and popping I hear at the problem RPM range.

Hi Everyone, Recently I have been having hesitation issues with my truck. It is a 1989 Pioneer with a rebuilt '93 HO motor swapped in. However, it is still using all renix sensors. My issues began about a month ago, after I accelerated quickly from a stoplight. When I slowed back down, I noticed that when slowly accelerating between 1500 and 2300 RPM my engine would hesitate and backfire. If I accelerated quickly, this was not an issue. I suspected that the TPS was having issues after reading online, so I cleaned the throttle body and tried to adjust the TPS. I could not rotate the sensor enough to get it to my required voltage, which was .83 volts. I then bought a new TPS and am still having the same issue of being unable to get it to the required voltage. I have also cleaned the dipstick ground and crimped new eyes on. Would this cause my rough slow acceleration? Why can I not clock the TPS enough to get to the required voltage? Also, I attempted to get on the highway the other day and the engine stalled out once I got to about 60 mph. If anyone has any ideas about what could be causing this issue, I would appreciate it. I am near wits end with this truck.

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I'll be sending my info your way!

here's my pocket dump. I always carry my Leatherman Wingman, its cheap, stainless, fairly strong and has a good 25 year warranty. I don't worry about beating it up, because it wasn't hundreds of dollars. Of course I carry my wallet, and my keys. My carabiner is made out of AISI 316 surgical stainless steel. It's good until around 70 pounds, which means it can be used to hang fairly heavy things if I need it to. I also carry my Schrade knife. Like the Wingman, this knife is well made, but affordable. Holds an edge fairly well, and I don't worry about beating on it. It too is stainless steel. Also I usually carry a cheap pen, which isn't pictured.