Horrible miss need help!!!

[Gearhead]

It sounds fine to me.... the lope coastdown is pretty common and not harmful. if the throttle is just too touchy that is tuning. How does it run going down the road.

See this video:
http://www.youtube.com/watch?v=Auz-uzygmjY&feature=plcp

 

[TurboM700]

I know you replaced them but double check your UCVH. I have had some from the factory that if you wiggled them they would miss. What I would do is take the VC off start the truck and start wiggling the harness and see if it makes a difference. They usually are the ones on the outside of the connector that I see the most.

But like others have said I think its normal.

 

[JohnnyBeGood]

It sounds fine to me.... the lope coastdown is pretty common and not harmful. if the throttle is just too touchy that is tuning. How does it run going down the road.

See this video:
http://www.youtube.com/watch?v=Auz-uzygmjY&feature=plcp

Mine never starts that smoothly. Everytime I start it it stumbles and romps pretty bad for a few seconds and then kinda smoothes out. Its also not that smooth coming down from free revving. It stumbles and romps sparatically when I let off for a few seconds then levels out. It does it especially bad when driving and I let off. I mean really bad. It'll sound like its running out of fuel and it about to die. Ill make another video at lunch so you can see what I'm talking about.

 

[Gearhead]

Mine never starts that smoothly. Everytime I start it it stumbles and romps pretty bad for a few seconds and then kinda smoothes out. Its also not that smooth coming down from free revving. It stumbles and romps sparatically when I let off for a few seconds then levels out. It does it especially bad when driving and I let off. I mean really bad. It'll sound like its running out of fuel and it about to die. Ill make another video at lunch so you can see what I'm talking about.

That is okay and since this is a fuel throttled engine, it is simply trying to maintain a constant idle speed so it only needs a few cylinders to do it. My daily driver with slightly smaller nozzles even does the exact same thing your truck does when it coasts down.

 

[JohnnyBeGood]

That is okay and since this is a fuel throttled engine, it is simply trying to maintain a constant idle speed so it only needs a few cylinders to do it. My daily driver with slightly smaller nozzles even does the exact same thing your truck does when it coasts down.

Well next week I'm sending you my chip and sending my injectors to jim to have a look at so we'll see what happens.

 

[Gearhead]

I don't think there's fault with any of the tunes.... also you can look at cylinder rotational velocity when running at idle warmed up. At 500 psi of ICP they should all be close to zero.

 

[JohnnyBeGood]

I don't think there's fault with any of the tunes.... also you can look at cylinder rotational velocity when running at idle warmed up. At 500 psi of ICP they should all be close to zero.

The are all 0 at 520-540 icp. I just ran 5 contribution test cyl.8 failed all 5 times and cyl. 1 failed 4 times.

Do you think a cracked piston could be causing my problem?

 

[4.0l sahara]

I would think it would have a ton of blowby with a cracked piston.

 

[JohnnyBeGood]

Well I haven't run a compression test but it has virtually no blow by on the "cap" test

 

[4.0l sahara]

and it sounds just like mine.

 

[JohnnyBeGood]

and it sounds just like mine.

I understand that alittle lope is normal but I promise you guys I'm not going crazy it's not running right. It's hard to tell from the video but if I took you for a ride or if u were standing next to it you'd know I'm I was talking about.

What do you guys make of the contribution test results?

 

[Tim @ P.I.S.]

Maybe i missed something here. But i agree it is not the smoothest idling 7.3 i have heard. But I have also heard alot worse.

Is the biggest part of your complant what you are hearing at the 2.13 mark in your video??

 

[JohnnyBeGood]

Maybe i missed something here. But i agree it is not the smoothest idling 7.3 i have heard. But I have also heard alot worse.

Is the biggest part of your complant what you are hearing at the 2.13 mark in your video??

Although that does seem weird to me know. My biggest complaint and concern is how spastic and inconsistent that kind of running is. It also just doesn't sound right when it's fueling. Sometimes it has a hollow stick against a tin can sound. SOMETIMES being key. The rough running and "miss" is never consistent. It changes sound rPm everything.

 

[PA Stroker]

sounds almost excatly like what mine is doing but my miss has gotten worse. i havent been able to try anything else on mine. its in the shop getting another new transmission.:fustrate:
but if i find anything out with my when i get it back ill be sure to post it up

 

[ryanss22]

I was the original owner of the inj that I sold to him, there were stock obs inj that i sent to rosewood and had built to 160cc/100% in my obs the idled the same, had a real lopey sound, and the inj after rebuild had a total of maybe 5k miles on them, and i was running tony wildman tunes...... I never had a problem and hope he can resolve his issue soon.... just saying this if anyone has any ? about the inj is all..

 

[JohnnyBeGood]

I was the original owner of the inj that I sold to him, there were stock obs inj that i sent to rosewood and had built to 160cc/100% in my obs the idled the same, had a real lopey sound, and the inj after rebuild had a total of maybe 5k miles on them, and i was running tony wildman tunes...... I never had a problem and hope he can resolve his issue soon.... just saying this if anyone has any ? about the inj is all..

No worries Ryan I'm not trying to pin this on you by saying it's the injectors even Jim says they're probably fine. But Jim being the awesome guy that he is offered to go through them and flow test them, I just pay for the ride and w.e parts if any need replacing. Since you sent them to him back in 2010 it couldn't hurt too bad to take him up on his offer. Plus when ups destroyed the box you sent them in one of the solenoids got chipped alittle and I know how sensitive they are and while passing the buzz test may prove that it's fine whats $50 for piece of mind.

 

[TARM]

Johnny if you think its not right then it likely is not right. No way anyone would have said anything sounded wrong with my engine idle and low throttle perf but I could tell it was not right. Sometimes it would change and hum so sweet but then others it was so different from it. But compared to how many run it did not sound bad just bad compared to how it sounded when it ran good. Blew a nozzle couple hundred miles later. I was pulling my hair out trying to figure it out before that. Replaced everything from sensors to HPOP, full pin out multimeter, every AE test there was. Nothing was obvious. Not saying you have a nozzle issue just an example of an similar experience.

Point being if you know based on how your engine runs that something is not right then likely something has changed and not for the better. Judging by Ryans comments it sounds like sending the injectors off to be gone thru and thrown on the flow bench is a good idea. Jim is a good guy from all accounts and sometimes things get out of spec range and cause issues.

 

[JohnnyBeGood]

Johnny if you think its not right then it likely is not right. No way anyone would have said anything sounded wrong with my engine idle and low throttle perf but I could tell it was not right. Sometimes it would change and hum so sweet but then others it was so different from it. But compared to how many run it did not sound bad just bad compared to how it sounded when it ran good. Blew a nozzle couple hundred miles later. I was pulling my hair out trying to figure it out before that. Replaced everything from sensors to HPOP, full pin out multimeter, every AE test there was. Nothing was obvious. Not saying you have a nozzle issue just an example of an similar experience.

Point being if you know based on how your engine runs that something is not right then likely something has changed and not for the better. Judging by Ryans comments it sounds like sending the injectors off to be gone thru and thrown on the flow bench is a good idea. Jim is a good guy from all accounts and sometimes things get out of spec range and cause issues.

Tram I agree 100% and I'm glad someone understands where I'm coming from. After running every test I can think off and quaruple checking everything I've decided to try another tuner and have the injectors gone through. Once I get everyththing back I'll throw it together and call it good. If it's still not right well then atleast Ill know I've exhausted everything I could think of sort of a full motor tear down and I'll just roll with it. I do appreciate everyone on here's input very much I just recently joined psa but I must say it's already my favorite board. I will keep everyone posted as to what happens after the new tunes and getting the injectors back. :thumbsup:

 

[JohnnyBeGood]

Ok was finally able to check my fuel pressure tonight(thanks again mike!). Was just above 50psi at idle. I'd say around 52-53. Sound low? Fuel system is stock other than DI in tank/ pre-pump kit.

 

[TARM]

No if it is holding the pressure constant and not swinging low and high then that is plenty of flow for idle. You would need to be almost no pressure for it to have issues at idle like you are having IMO.

But I would recommend you get a RR on there or at the very least that quasi one by Riff. Also make sure to use a top brand of filter if you are keeping the bowl. DONOT USE NAPA OR WIX. Donaldson Racor are good and I know for sure are 5mic absolute. NAPA and WIX are WAY larger in mic size. Do not use any of the auto store brands FRAM, Car Quest, etc... Ideally you want to be in the 2-3 mic range absolute (98% or better) but you will not get that in the fuel bowl version. Personally I would do it right once you get this injectors back etc. Dump the bowl and add two filters one pre and the other post pump. The only costly part will be the regulator. The rest you can pick up for under $200 if you are keeping the stock pump and it will hold pressure @ WOT I can give you a parts list to do or get a kit from one of the vendors. You could do the whole thing for say $350.

Want your injectors to last feed them clean oil and clean fuel. The cleaner these fluids are the longer they last IMO.

Hope it ends up being the injectors. That is where my bet will be between tunes and injectors. But Matt does make very nice tunes power is a given but they shift great lowest smoke I have seen IMO.