High RPM lean?

[SilverXJ]

I don't think this is a cam issue. If it was running out of steam at 4200 all the time I would think cam.. however, it only does it once it warms up.

[Brian E]

I feell this too but since the only thing that was changed was the cam last time and thats when it happened it makes me lean that way. I also see that he advertises that Elgin cam in his listing now and since kptuk is having the same issue it also leens me that way. And since I do not beleive they tell the truth on anything I do not beleive he put the Comp Cam in his. They have lied to me about so many thing now I can not count. Pistons, piston coatings, cam, timming chain, cylinder head, oil pump, valve springs none of these are what he said. The oil pump is a basic 8am1 mellings not high pressure, the timming chain is not double roller, the cam is not the same spec as he stated, he said he would not put another 0331 head on it he did, the valve spring are stock seat presure I had them tested and theres no way for the price he had the pistons coated nor the brand hypertutetic. My cam was supposed to be .476 and it is .447.

[Brian E]

You might try this and post up. I went through EVERY FORUM POST ON HESCO and now my head hurts. I read a very old thread on there where a guy was having the same issue, he never responded to the final results which makes me wonder if it fixed it because he never asked any more questions. The guys 97 TJ would run great till it warmed up then would not rev past 4200 - 4300. Lee told him to put the IAT sensor out side the hood area to test it. When it starts to warm under the hood and the intake temperature rises it takes away from total timing on the top end and will not let it advance past 26deg, it needs a total of 31. Some aftermarket cams change this. You could also try advancing the crank sensor 4 deg. I did this years ago to a 2.5 jeep and it really helped. FYI in case you are not sure I am saying move the crank sensor not the distributor. I elongated the holes in my crank sensor and moved it. I would try this but I got mad last night and gutted my whole motor. I am sending the head and laying out a valve train set up with Dave Rumping in Gainesville. For any of you interested Dave is like the race car engine guru of the world. He has had cars on the cover of 5.0 magazine twice. He also built an engine for Lugo Performance in Orlando, a v6 in a supra that put over 900 horse to the ground! How about a 700HP 4cyl twin Turbo Toyota. And just recently he did a 2.5 Jeep motor for his Wrangler .30 over decked shaved head .450 cam ported head and port matched, bored 4.0 throttle body and modified timing sensor. 4.88 gears 35" Irok bias tires loaded jeep with all the goodies for rock crawling, tools, spare tire, on board air, winch, heavy bumpers, exo cage, rock rails. I ran along side him in a head wind he maintained 75mph in 5 gear with no problem and can even excelerate. I have known Dave for years, his work is amazing. I have seen him fix thing for major groups like Mercury Marine racing Powered by Ford and Rev Master when they messed it up. Sorry such a long post I was under the hood all night and I am about to die.

[kptuck]

Well I am back on task trying to figure out this issue.

I took a little time away from it to calm my frustration and think clearly.

The last things I did were to replace the injectors with a brand new set from five-O. I also replaced the MAP sensor...

The issue is still present. Runs good on a cold engine and runs bad on top end on a warm engine.

I plan on calling Hesco today and askign for new advice. The IAT reading is actually an interesting thought. But my crank sensor goes through the bell housing and there is no way to manually advance it. I have been getting an IAT reading of 190 degrees F. I know this is high and tried removing the IAT sensor and pluggin the hole in the intake. This dropped the IAT to 130 degrees. I still only have 26 degrees of total advance, well to be more specific the pcm gives up to 40 degrees of advance and then pulls back advance as my revs go up, in my problem area the total advance stays at 26 degrees. We have had temps of 100 degrees ambient for the last month +

This seems way low to me as I expected a total advance of 30 to 32 or so...

Does anyone else know their IAT readings in an engine that runs properly?

Thanks

[kptuck]

OK Bennie at Hesco said to stop looking at timing. I is controlled by the pcm and is not adjustable. 30 degrees is the most I can get anyway at RPM.

His thought is to try advancing and retarding the cam sensor and try it, and to see if I could get another pcm to test in my vehicle.

[kptuck]

Hello Stroker forum . Well it has been quite a while and basically the issue has never changed. I did install a Superchips 3875 Flashpaq, which helped bottom end, but did not fix high RPM issue.

I talked to BG Chrysler today http://www.bgchrysler.com/Service/service.html

They said for $350 they can reprogram my PCM and solve the issue... So I am finally ready to deal with this issue again and am boxing upp my PCM as I write this post.

The Jeep runs great up to the 4200 RPM wall, so all I have been doing is letting it shift earlier than that. Very happy with the lower RPM performance, just need to fix it so I can floor it and forget it!!

Has there been any similar issues in the past 6 months? I did a look but did not find anything exactly like mine.

Kevin

[SilverXJ]

Any luck figuring this out?

[F1boats]

I have the exacted problem have tried everything like you ! Guess I have to send my box out to errrr

[Brian E]

Did you ever get this fixed? Mine was not a lean issue as I had thought. My valve springs were way out of spec for the cam I had. Had them set up right at Dave's Machine in Gainesville Fl and never looked back, I couldn't I was going to fast

[93turqxj]

did you ever figure this out same problem except mine does it all the timein park or under load cept at 3800 rpms

[Mopud]

I'd love to hear a report back on this one as well.

I'm exactly the same - running lean on a hot engine on WOT. Same injectors, big bore throttle body, 68-231-4 cam, replaced cps/ckp/o2 sensors, changed cat - the whole shebang! Idling and metro is fine - even when i punch the throttle. A real hot day though with high under bonnet temps sees it pinging at the top end.

I have no heat shroud or insulation for my fuel rail however, even the factory stuff isn't on there. That's my next step, i think it might be vaporizing before it enters the cylinders.

[SilverXJ]

Now you are confusing me.. i though you had the flashing CEL? You have a lean issues as well?

[Mopud]

Yes, sorry Chris i mentioned this in the initial post on my thread. Apologies, perhaps I should have repeated this in subsequent posts. It is as described here - gets a bit rattly at the top end but only when it's well and truly warm.

No engine codes and the lean condition has never ever triggered a code for as long as i've had the vehicle. The flashing CEL is a recent issue which i've only been experiencing in the last month or so.

Even after my unichip install and dyno tune(s) it still exhibited this symptom.

Anthony