Having multiple issues after stroker motor install

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mrd05d

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Sep 11, 2021
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Location
Tampa FL
2003 Jeep 4.6 Stroker with 42RLE

Old 4.0l died of piston slap. I built a Titan Engines 4.6L and swapped it in did cam break in etc. All seemed to go ok however I'm having a couple issues I can't seem to figure out.

Idles and Drives okay. However it hunts for idle after coming to a stop sometimes after cruising. It was stalling out prior to a new battery. Now it doesn't stall just sometimes misses idle when coming to a stop and drops to 250rpm or so then hunts for correct idle until it finds it a couple seconds later.

I also noticed when its idling if I blip the throttle the rpms drop until it "catches up". It is like a hesitation reading the tps or something, I am not sure how else to explain it. I could post a video of that If I need to.

The last issues I am having with it is that it will not shift if I go WOT from a standstill. Almost like it doesn't ever reach the proper inputs to shift when it should have already. If I am driving already it will upshift fine at WOT.

I am hoping to figure out these issues. I feel like I am so close to getting this thing running mint but feel so far away at the same time.

So far I have done the following:

Replaced Crank Sensor (it was cracked when putting the engine back in) - Mopar
Replaced TPS - Mopar
Cleaned IAC (Didn't Help)
Cleaned ThrottleBody
Replaced IAC - Mopar
Replaced Bad Battery - Was dropping to 6V when under load
Cleaned grounds
Upgraded to BIG 7 2GA Kit from Jeepcables.com
Upgraded injectors to Bosch 0280155784 to bring fuel trims into spec (+3-5 now)
 
Overall sounds like it might be a ground issue. The TPS and allot of other sensors use 5V from the PCM to work, if the grounds aren't in really good condition the 5V wont really be 5V so things will get all messed up. I'd check the harness grounds, the one on the block and firewall to be sure they are in good condition. It might also be the connector to the TPS or the wiring to it, you might take a close look at that too.
 
Thanks for the response,

I cleaned the grounds already, took sandpaper to the surfaces under the ground bolts as well as each of the eyelets. The Big 7 install also included 2ga grounds from battery to block and battery to frame. Not saying it absolutely can't be grounds. But I definitely checked them and cleaned them already.

Min/Max and a smooth sweep test for the TPS (old one and new one).
 
Just a thought, maybe source another IAC and check? I have gotten a few faulty Mopar electrical parts from dealers over the years. If you got old ones, try those (both TPS and IAC) and see if anything chnages?

Check spark plugs? Coil packs?

Why Titan? I am also looking to do a stroker build soon.
 
I went with a Titan Kit because it was easy to get for me as I live 30 minutes from their shop. I have heard bad things about them but also good things. So far my opinion is on the good side vs the bad. But I did the assembly myself.

I'll look at swapping sensors and I have a coil rail i can swap too.
 
It might be a long shot but possibly a faulty crank sensor? I've heard of others having issues with brand new sensors, even Mopar sensors. A good friend of mine had idle issues like what you're describing with a brand new engine. He went thru a handful of CP sensors before finding one that provided the correct idle.
 
I have another new Mopar crank sensor i can throw in.

When you say Sync the cam position sensor what do you mean?

When putting the cam sensor in I ensured It was TDC put the oil pump keyway at 11pm and used a tooth pic to line up the outside casing hole and inside hole of the cam sensor. Is there something else that needs to be done?

There is no CEL/Codes. It will start immediately and idle forever Just fine. Other than skipping a shift if I WOT and wanting to stall /hunt for idle when i come to a stop it runs fine.
 
@Brianj5600, I found this in all data... I did not verify with Scan tool. I will do this tomorrow if i can get around to it. Thanks

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I hooked up fuel gauge. It's showing 45psi at prime and when i start it the gauge fluctuates up and down from 38 to 52 like crazy. I ordered another fuel pressure gauge to make sure this gauge isn't bad but it wont be here for a couple days.
 
Finally got the new fuel gauge in today as well as a fuel pump just in case... I also swapped in an older IAC from a WJ i have and the idle seemed to smooth out. However I drove her for 20 minutes or so and she did stall at a light again. It seemed more random of a stall this time though vs idle hunting and sputtering until it died. I will being driving it around more tomorrow trying to get the gas tank as low as possible for a new pump...
 
Also wanted to mention today I upgraded to 160 amp Alternator and Viper coil instead of coil rail. It didn't do much of anything noticeable but now i can check spark/change plugs etc without having to unbolt rail etc...
 
No mention of what you did for a tune. Are you still running a stock 4.0 tune?
 
Yeah stock tune. I haven't done TB or exhaust. If/When I decide to do those I'd look at tuning....
 
With the stock tune on the stroker, my guess is you maybe running lean, which could be causing some of your trouble. But, that is just a guess, and hopefully someone who knows better will chime in. When I stroked my Hemi, my engine builder told me not to even run the thing before getting it tuned because it would be lean enough to do some damage.
 
I had an idle hunt issue due to a small vacuum leak that wasn’t enough to throw CEL. Might smoke test it and see what’s leaking. I found three small leaks and fixed my hunting issue.
 
I just did a stroker swap. I don't have the skills to build my own like you, so I bought a Golen engine. My TJ is a '97 w/ an AX-15. It has the stock tune with 62mm TB, 24# injectors (stock is 18#), and a header. Initially my idle was higher than with the 4.0 (800-1000 rather than 600-650). This was erratic; occasionally the idle was normal. And otherwise, it drove very well. After doing some reading, I decided to swap the O2 sensors (the 97 only has 2-upstream and downstream) from Bosch to OEM Mopar units. That fixed the idle issue completely. I'm not sure if that helps, but I thought I'd share the experience. Good luck.
 
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