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Something I just noticed

1K views 8 replies 5 participants last post by  jesilvas 
#1 ·
Ive had the truck for about 2 weeks and put about 300 miles on it, its run great and had no problems at all, but here is the thing.


Tonight I was stopped in my driveway sending a few text messages right before I shut my truck off and went inside, and this is really the first time I have sat in my truck with it idling for this long approx 5mins.


The idle sounds great, no problems in power ect but every ~10 seconds the idle jumps up a few RPM and then goes down ( maybe 600-650rpm? barley noticable on the tach, and you have to listen for it).

The truck had just been driven, and the heat was pretty warm ect.


The truck has the 10k mod, 4" exhaust , napa intake and some FPR shim to 62 psi ( done by pervious owner, told it was 61 or 62 psi)


Is this something i should look into before somthing breaks? or is this not a big deal. Anything i can check?

like i said the idle doesn't sound bad..doesn't sound like a miss or anything its not that apprupt, it just seems to not be 100% consistant idle rpm, theres a rythmic raise and drop (idle at 600 rpm for 10 seconds, then spikes to 650 for 1 second, drops back to 600 for another 10 seconds ect)

Thanks a lot!
 
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#2 ·
Just changed oil like 100 miles ago, and it looks clean on the dipstick( heard bad oil can make these things actually run worse!)

oh, and I heard the truck idle for like 30mins while looking at it when i purchased, it didnt do this if i remeber correctly.

but the difference is, he didnt have the 10k mod plugged in, he was running some edge programer tow safe hp boost thing, and he said the 10k mod didnt work with the tune, then he plugged the 10k mod back in before he sold it to me.

maybe its just the 10kmod? i heard it could make the idle rough?

thanks again!
 
#3 ·
I bet it did do it when u purchased it....but you were too excited and didn't notice...lol! Seems like both my 97 did it...my buddies 97s do it and people on here with 97s ask this question alot. Good luck!
 
#6 ·
It's just HPO pressures raising and lowering. It happens. Nothing to worry about.
 
#7 ·
Yup, i probably didn't notice it, outside the truck its extremely hard to tell its happening. I can only really tell in the truck pulled into one part of my driveway were the sound bounces off just right, or when i stare at the tach lol.


Not sure if anyone will look at this thread ever again, but i have a small oil leak, and i believe it might be my HPOP, theres a nice kit on ebay for 50$ full reseal kit, its for a 99-03 though...and im 97 :'(

whats the difference? as far as i know they only added a waste gated turbo, an intercooler and maybe some pcm stuff?


thanks for all the help guys!
George
 
#8 ·
Happened in both my e99 and my 02, its completely normal.

the HPOP differences are your have a 15* HPOP, 99.5-03 7.3's have 17* HPOP. I'd look for a 94.5-97 reseal kit.
 
#9 ·
Read up on the HEUI system, you'll find out why oil is important.
Mine does this. It's the HPO pressure fluctuating. #6 fires right before #8 and it depletes the fuel and oil rail for the #8. So it's just the truck keeping up and then not :doh:
If you really wanna fix it that bad, put a bigger HPOP on it or get an HPx. Hard line though. Have gone through two rubber lines.
Also, the SDs had a 17* HPOP. OBSs 15*. Different injectors. Electric fuel system. So on.
The Edge is just a glorified 10K mod almost. The 10K resistor mod changes the signal coming from the ICP to the PCM so that the PCM thinks you have less HPO pressure than you do, causing the IPR to increase duty cycle of the HPOP, therefore raising pressure.
 
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