Engine hesitation
- Thread starter RicanCrazy
- Start date
Update. Ignition coil came in. Had to modify the bracket due to the newer ones having the plug in the other side of it instead of the original same side. After doing so there was no change in cold start pedal power loss. Only thing I'm waiting for is the ECU to arrive to have the last thing I can think of
Random thoughts:
Have you tested for a vacuum leak when the engine is cold?
I’ve read that a bad coolant temp sensor can cause problems.
Maybe try a tps sensor (since it’s involved with acceleration).
If u get real desperate, maybe try a crankshaft sensor, Cam position sensor, or Map sensor.
Have you tested for a vacuum leak when the engine is cold?
I’ve read that a bad coolant temp sensor can cause problems.
Maybe try a tps sensor (since it’s involved with acceleration).
If u get real desperate, maybe try a crankshaft sensor, Cam position sensor, or Map sensor.
Unfortunately I've replaced everything already. And no vacuum leaks. Have also replaced the cracked exhaust header and gasket. Basically everything under the hood has been replaced minus the coolant temp sensor due to me not thinking a coolant temp sensor will cause the vehicle to try and bog down when pressing the gas?
Damn dude.
Supposedly, if the coolant temp sensor thinks the coolant is hot even when it’s cold, it can cause problems. I haven’t experienced it myself but I’ve read about it. There might be more to it than I’m able to explain. Or it could be a waste of time. Figured I’d mention it and let u look into it since things are getting a bit desperate.
Could u have an evap issue? Is the solenoid working properly?
Where would I look for the solenoid on my 99 4.0 auto Sahara? I'm literally down to crumbs left on what I've changed in the engine bay. Sad part is she isn't even showing codes on what's wrong. Also no coolant in oil and no oil in coolant. It's crazy that I've changed so much in the engine bay and there hasn't been any change....
Side note, someone was mentioning a vacuum container the jeep might have. Would that be an issue that can cause my symptoms? And if so where would it be located on the Jeep?
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Isn't there a vacuum canister under the battery tray?
On my 97 the vacuum line Ts at the heater/AC lines...where they go through the firewall above the battery...and then heads down to the canister.
Saying that cause you could disconnect it and cap it off as a quick and dirty test before digging out everything else in the way.
-Mac
I believe he said he tested for vacuum leaks. I agree with confirming this though. I’ve had great results using a smoker device that connects to compressed air.
Yeah I tested at the main lines from the intake and around but I didnt know the lines went down to a box. I'll have to check that.
Update. Remanufactured ECU came in and had no change. But as I was poking around the throttle body, I noticed when i wiggle (not lift or push down) as it was idle, the idle went up without opening the throttle. It may be I need a new Throttle body.... Can someone confirm if you just wiggle the lever it shouldn't raise the idle? (I didn't manually move it, just wiggle left and right slightly.)
It could be a vacuum leak at either end of the butterfly valve shaft, and the RPM increase when moving the bracket might be from air getting sucked into the system. But, IIRC, you said there were no vacuum leaks? I'd confirm this.
The seals in the bearings of the butterfly shaft degrade and allow air to pass.
I replaced my seals with Orings from a metric harbor freight kit.
Generally, you just:
- remove the TB,
- remove the TPS sensor
- remove the throttle plate
- remove the butterfly shaft
- remove the old seals with a scribe (from the inside and outside of each bearing).
- install two orings on the inside of each bearing (inboard of the needle bearings). Note: I used a light amount of silicon grease on the orings.
Mine used to leak terribly bad and prevented me from getting into light boost. There was no leak at all yesterday when I did a boost leak test on the system. If it can hold pressure then it can hold a vacuum.
Here is a thread that talks more about changing the Orings. No need to chamfer the end of the butterfly shaft (the end that cams into the TPS sensor), but I did on one of the TBs before I realized it's not necessary (and it won't hurt if you do).
I've sprayed tons of spray around every vacuum hose and the throttle body. No increase and no breaks in the lines.
Knowing what I now know, I wouldn't trust that method or recommend anyone trust that method.
Keep in mind that some leaks don't occur until there are vibrations or expansion from heat or pressure.
Here is a link to a better option (pressurized smoke tester)...there are other comparable options out there (eBay for example). You simply need a car battery and shop air to make a kit like this work (assuming you don't run out of oil, which I replaced with this oil because it's much cheaper than the official stuff and research showed that it would be safe and work well for me...but DYOR).
The pressure helps the smoke expose leaks that you didn't know were there. I like to keep a bit of soapy water around when doing the tests as well.
Edit: For example, you can't really get spray to inside/behind the TPS sensor to know if you are leaking from that bearing. But smoke will certainly come out, and soapy water will expand if you pressurize the system with as little as 2-3 psi of regulated shop air.
Well the complete opposite is happening. It stops the cold sluggish response after it is warmed up. But in return I lose power around 45-60 mph when warm.
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