Uphill power loss, help

[RMR Motorsports]

Ok this is what is going on, when I'm going up 6 percent grade in OD it's like someone threw out a boat ancer and have to pull it down to D and doing about 45 mph uphill, also when rock crawling I got to put in 4x4 low. This is what I have, 4.0 ohv v6 with 410 comp cam, MAHLE heads ported with guides shorten for comp dual valve springs, smothed out TB, fabed 3" cold air intake system with S&S filter and 70mm MAF, Bosh injectors, brola headers, high flow cat, cat back exhaust system with flow master muffler, I've had problems with the exhaust guides wearing out causing to smoke and tapping noise at times, removed heads had rebuilt installed rebuilt lifters and rocker arms, did the comp cam run out cam up push rod lenght 5.500, installed 5.550 push rods I had, now it's smoking again only if idle long time and tapping at times. The tranny is an A4LD that's been rebuilt with all updates and shift kit, also had low end tourque converter built by Hughes and trans cooler, the tranny would spit out trans fluid when I was going up this really steap mountian road and had to put it in 1st to get to the top, stock TC, limited slip stock rear end with 4:56 gears, front stock with 4:56 gears with lock rite locker, 33" tires, with all this work I've done it should run like a raped ape. So if anyone has any idea please let me know thanks

 

[4x4junkie]

Dang, that's a lot of mods you have on that engine..

All I can really offer is my own experience...
I had an issue with my stock '94's 4.0L suddenly losing power on long grades (and also while towing trailers) and it ended up being fouled O2 sensors from using a K&N air cleaner (it would also throw a CEL with multiple codes indicating MAF out of range, and both cylinder banks "at adaptive limits" lean or rich (I forget which one, or maybe it was actually both... it was a very confusing set of codes lol).
I replaced the sensors, and cleaned the MAF and the problem was fixed (I also switched back to a paper air filter to avoid a repeat of this issue).

Hope maybe that helps.

 

[RMR Motorsports]

Thanks 4x4junkie I do use filter like a k&n and have gotten MAF code too, when you had this problem on start up sometimes sounds like misfire or not running on all cyclinders?

 

[tweakedlogic]

start with a comprehensive tune up and go from there.

 

[RMR Motorsports]

I checked fuel pressure, checked out ok, I've cleaned MAF and air filter, I was thinking next spark plugs and 02 sensor. any other sugestions or what to check for?

 

[jd4242]

Ok this is what is going on, when I'm going up 6 percent grade in OD it's like someone threw out a boat ancer and have to pull it down to D and doing about 45 mph uphill, also when rock crawling I got to put in 4x4 low. This is what I have, 4.0 ohv v6 with 410 comp cam, MAHLE heads ported with guides shorten for comp dual valve springs, smothed out TB, fabed 3" cold air intake system with S&S filter and 70mm MAF, Bosh injectors, brola headers, high flow cat, cat back exhaust system with flow master muffler, I've had problems with the exhaust guides wearing out causing to smoke and tapping noise at times, removed heads had rebuilt installed rebuilt lifters and rocker arms, did the comp cam run out cam up push rod lenght 5.500, installed 5.550 push rods I had, now it's smoking again only if idle long time and tapping at times. The tranny is an A4LD that's been rebuilt with all updates and shift kit, also had low end tourque converter built by Hughes and trans cooler, the tranny would spit out trans fluid when I was going up this really steap mountian road and had to put it in 1st to get to the top, stock TC, limited slip stock rear end with 4:56 gears, front stock with 5:56 gears with lock rite locker, 33" tires, with all this work I've done it should run like a raped ape. So if anyone has any idea please let me know thanks

i think you need to prof read this because some of it doesnt make sense.the 410 cam doesnt require 988 springs but are helpful.did you have the heads machined to fit the springs?are you wearing out the guides or seals?sound to me the heads were not machined for the springs and are hitting/not fitting right.more needs to be done than just shorting the guides,the seats need to be milled or the spring wont fit right and not allow the valve to open all the way.was you running 5.500 pushrods,or is that a typo?with 5.500 are way to short!!
when going up step grades you should not be in OD and 4x4 low range is needed for steep grades offroad.how do you build a low end tq convertor?never head of that.that 70mm maf is hurting your performance.you basically still have a stock truck with a little better cam and exhaust,maybe 15 extra hp.these truck are very heavy and dont have the right gearing.if your doing alot of step grade driving or climbing then you should have went 4.88 for sure.get a trans temp gauge,im sure you are overheating your trans and thats why you are losing power

ps you have 5.56 in the front and how is it stock with 5.56 and a lock rite?

 

[4x4junkie]

Thanks 4x4junkie I do use filter like a k&n and have gotten MAF code too, when you had this problem on start up sometimes sounds like misfire or not running on all cyclinders?

Mine never acted up at startup, mine would go weird after having been laid on the throttle for an extended period of time (first started noticing it near full-throttle, but as the issue progressed, even 5 minutes straight at 2/3 throttle was starting to do it).
Driving it around town or on a flat interstate (not towing) with the throttle at 1/2 or less, it was fine.

It was a sudden 50% or so loss of power, and would also start guzzling fuel too (no misfires or roughness). The CEL would come on and go off in like 5 minute intervals repeatedly during this time.
Flooring it would often "bump" it back to full power for maybe 20 seconds, but then it would slump off again right away.

Best bet probably is to go by the codes your PCM sets, but try to think how systems can interact with each other. The MAF and O2 sensors are both used by the PCM to control fuel mixture for example. If you're getting a code for something being "out of range", say, there's always the possibility it's not the sensor it's flagging that's malfunctioning, but another sensor that's part of the same system (in my case, there was no problem at all with the MAF. Even with cleaning it my issue persisted until I replaced the O2s).

 

[92exploder4dr]

4.56 in rear and 5.56 in front and you run in 4WD?!

 

[jd4242]

4.56 in rear and 5.56 in front and you run in 4WD?!

Bahah thats obviously a typo

 

[Naasau]

You're right about the power assertation, I'm bone stock in the engine compartment with a beat up A4LD and 3.73 gears, and even pushing 285/75r16's I can still accelerate up I70 into the mountains, 6-8% grades (I think) and top out around 85mph. My point is with all the TLC you've given your monster is should be able to beat the living hell out of my beast, but that's not what it sounds like it's doing.

So.. I'm no where near as smart as the other guys here, but odvious question time, have you checked the compression on all of your cylinders?

 

[RMR Motorsports]

jd4242 the heads seats where machined for the 988 springs and the exhaust guides where wearing out not seals, after following the comp cam run out to get push rod lenght I got 5.500 but had 5.550 push rods from smith brothers and I thought it help with preload on the lifters, my friend own's a tranny shop and at the time no one had a low end torque converter so he called hughes and they built one, ok you got me type-o fixed it, on front diff gears there 4:56 with lock rite locker in a stock 35 diff, from the sound of it you know this motor and that pic with your post looks mean, so the 70mm MAF is not helping? if you don't mind I would like to talk to you, thanks all with this.

 

[jd4242]

jd4242 the heads seats where machined for the 988 springs and the exhaust guides where wearing out not seals, after following the comp cam run out to get push rod lenght I got 5.500 but had 5.550 push rods from smith brothers and I thought it help with preload on the lifters, my friend own's a tranny shop and at the time no one had a low end torque converter so he called hughes and they built one, ok you got me type-o fixed it, on front diff gears there 4:56 with lock rite locker in a stock 35 diff, from the sound of it you know this motor and that pic with your post looks mean, so the 70mm MAF is not helping? if you don't mind I would like to talk to you, thanks all with this.

Yea 5.500 is way to short.gotca hmm is it still wearing them out? You running stock valves?yes the 70mm is putting you at the max your ecm can adjust for,unless the maf is tuned to your ecm or if your ecm is tuned for the maf.you have no codes right?do you have a trans temp gauge?you can PM me anytime if you dont wanna post a question on here,goes straight to my phone and i never mind talking trucks or motors

Ps that pic over there was my first motor,ive upgraded three times and now doing a supercharger

 

[RMR Motorsports]

jd4242 I PMed you, yes stock valves, the 70mm MAF was programed to engine mods, no codes, don't have trans temp gauge, don't know if wearing out guides again but it smokes at long idles and no oil leaks but have to add about a qt of oil a month.

 

[RMR Motorsports]

forgot to add running 5.550 push rods not 5.500, when I talked to Delta Cam they said they run 5.525 push rods with the 410 comp cam, so I thought I would be ok.

 

[bullrush]

Might be way off but maybe look at replacing your fuel pump, mine used to "die slowly" up hills on the highway, my fuel pressure was ok but my fuel delivery was terrible, put a new fuel pump in and she is a 1000 times better, no longer need to drop into 4th to get up hills! Just something to check, cheers

 

[RMR Motorsports]

bullrush what do you mean die slowly? did your X die or just loss of power? I have thought about the fuel pump, psi test good, but on cold start up it acts like mite be out of fuel sometimes, like not holding pressure and bleed back, did you have this problem?

 

[RustySJohnson]

Smoking at long idle? Worn out fuel pressure regulator allowing fuel into the vacuum lines maybe. Mine did that, it was a dog. Ran rich and the ecm never could compensate.

 

[RMR Motorsports]

Thanks RustySJohnson, that also maybe the cause of loss of fuel pressure at time during cold starts, here's a pic of my engine.

 

[bullrush]

bullrush what do you mean die slowly? did your X die or just loss of power? I have thought about the fuel pump, psi test good, but on cold start up it acts like mite be out of fuel sometimes, like not holding pressure and bleed back, did you have this problem?

It just lost power up hill to the point when I had to drop to 4th, I would replace the fuel pump anyway (probably never been done and she is an old girl) My mate (and mechanic) did a fuel pressure test and said the pressure was good but then checked the fuel delivery and apparently that was 1/4 of what it should have been.

That was 100% my problem as my truck is a completely different vehicle now. Only problem is to replace the fuel pump you have to remove the tank (sure there are threads on here). It sounds like this could be your problem, maybe check or get someone to check the fuel delivery, you will probably find your fuel pump is not pumping enough fuel through on the uphills or is faulty, let me know if this is what is wrong! Good luck!

 

[RMR Motorsports]

jd4242 I PMed you, yes stock valves, the 70mm MAF was programed to engine mods, no codes, don't have trans temp gauge, don't know if wearing out guides again but it smokes at long idles and no oil leaks but have to add about a qt of oil a month.

Did you get my PM and are you ok with it?