Jeep Wrangler Surging

It is difficult to see on that pattern but it appears the closing pintle hump may be missing. Chrysler commonly uses the inductive kick to verify injector operation. If the closing pintle kick is missing , erratic or not strong enough it may be skewing the modules perception of the injector circuit. Do all 6 patterns resemble his one? How is the current pattern? On the current side watch for…

Hi Robert, Thanks for the reply. All the patterns are like this one. I think the pintle hump issue is more the limitation of this scope than it is missing. If you look closely it is camouflaged by the second grid line up. I like your point about the current flow. That could be it. One thing I did not mention is that the longer I ran the vehicle, the more injectors showed with the same variety…

I would want to make sure that the Jeep had the correct injectors and pcm before going further.

I'm wondering if someone else has already installed AM injectors that are flowing the wrong amount of current...(and maybe fuel too!).

How’s the charging system? AC ripple OK? I would still check current as it will show you the rest of the picture. There may only be one faulty injector and due to internal circuits in the module it may set codes for multiple injectors.

Agree...I saw a case study on a Toyota that had one bad injector, caused system lean and multiple misfire. Current would definitely help narrow the possibilities.

Have you scoped the throttle position sensor? It used to be pretty common that a dirty signal on the TPS usually around cruise speed would set injector codes like that. If I recall the rapid change in the TPS signal would cause the PCM to go into acceleration mode when it shouldn't.

Did you volt drop any of the injectors harness? You might try a FRTD and watch the O2's on WOT to see how the fuel pump is performing. Hope that helps.

Look closely at the inductive kick on all injectors. The only ones I have seen were related to the height of the kick.

I know you said you didn't have a way to test fuel pressure​.​What about a current ramp test with your meter.

These captures are from an 06 Jeep 3.7L CH A is injector 1 volts CH D is a WPS500 on one side of the fuel rail. The low fuel pressure drops are from the injectors on the far bank. HTH

Here are the things I would check based on what I have seen in the past. Do a TP sweep, what happens is right around that 10-20% throttle range the voltage may spike to double what you would expect. The PCM quickly increases the PW and sometimes it sets injector circuit codes. The PCM of this era did not do a good job coding for TP sensor issues, especially without a MAF they probably could not…

Hi there it looks like the inj spike is clip at 69v which is good. I will assume all are equal. Current ramping all inj for common looking ramp wld be a good confirmation that they are ok electrically. I wld doubt an actual inj fault but there may a common feed resistance. on V side check all inj and being pulled down to 0 v on turn on. it does not sound like one inj but all if it is the inj, so…

Thanks all for the comments. We will see if the customer calls me back. They were going to check fuel pressure at the rail to see if it is low. It seems that there is a filter and bypass regulator in the module assembly. Maybe something there is haywire. I do appreciate all the comments on the wiring and injector problems. Lots to go with here. We will see how it sorts out. BTW the engine runs…

We have had several that had bad connectors on injectors .we have been replacing all .