Mild Push/Pull | Stumble after cam install
Thread Starter
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Laughing Gas
Joined: Apr 2011
Posts: 913
Likes: 7
Mild Push/Pull | Stumble after cam install
Goodmorning all,
Just put a comp cams 31-255-5 and lifters in my 88 302 F150.
Truck is still speed density, Autolite 25's, MSD cap, rotor & coil, 9mm FR wires, GT40 upper/lower, 65mm TB.
Also still hydraulic flat tappet. Put a new timing set (cloyes) and dampener, and water pump/tstat while I was at it.
Truck is idling fairly well, just finished up the 30 minute break in period with the ZDDP additive.
I'm getting a mild push/pull, kinda of stuttering at higher rpm (4000? 4500? Only experienced it once.) It doesn't seem to be any kind of interference issue, almost reminds me of ignition stumbling.
Ideas?
Just put a comp cams 31-255-5 and lifters in my 88 302 F150.
Truck is still speed density, Autolite 25's, MSD cap, rotor & coil, 9mm FR wires, GT40 upper/lower, 65mm TB.
Also still hydraulic flat tappet. Put a new timing set (cloyes) and dampener, and water pump/tstat while I was at it.
Truck is idling fairly well, just finished up the 30 minute break in period with the ZDDP additive.
I'm getting a mild push/pull, kinda of stuttering at higher rpm (4000? 4500? Only experienced it once.) It doesn't seem to be any kind of interference issue, almost reminds me of ignition stumbling.
Ideas?
Thread Starter
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Laughing Gas
Joined: Apr 2011
Posts: 913
Likes: 7
That's what I figured. Should I go ahead and unhook the battery to do a full reset? I had it hooked up the whole time during the install.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Well that is not good... the battery should be the first thing disconnected when doing any work on the motor... otherwise you risk damaging the PCM.
But it won't make any difference now.. it won't help it adapt any quicker.
But it won't make any difference now.. it won't help it adapt any quicker.
Thread Starter
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Laughing Gas
Joined: Apr 2011
Posts: 913
Likes: 7
I'm still having this issue, any ideas?
Edit:
Let me fill in some info holes here.
Truck just ticked over 85K miles total. I have about 600 miles on this oil change, did the ZDDP break in additive and everything.
I'm getting a stutter/hesitation that starts around 4400-4500RPM when in drive, normally to reach this RPM while accelerating you have to pin it to the floor, but if you let it run into this stumbling area and let it upshift, the stumbling will continue to occur for a few seconds, then it evens out perfect.
Tuned
Joined: Sep 2014
Posts: 358
Likes: 7
From: Ky
Though I'm not completely read up on the subject, and I'm thinking this would have been mentioned, don't these engine controls have a rev-limiting feature at a certain RPM?
4500 RPM sounds a little high, is it really at that number, and does it happen when actually driving the truck?
4500 RPM sounds a little high, is it really at that number, and does it happen when actually driving the truck?
FTE Chapter Leader
Joined: May 2006
Posts: 12,344
Likes: 1,318
From: Central Mississippi
Would like to see some shots of this on how you adapted this to your pedal/cruise & etc. (if retained)
Any codes? What water temp, fuel pressure/you got a gauge?
What do the plugs look like?
Any codes? What water temp, fuel pressure/you got a gauge?
What do the plugs look like?
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Tuned
Joined: Sep 2014
Posts: 358
Likes: 7
From: Ky
It looks like your edit may have answered part of my question.
I probably would be thinking that it was starving briefly for fuel, air, or both.
I probably would be thinking that it was starving briefly for fuel, air, or both.
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Thread Starter
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Laughing Gas
Joined: Apr 2011
Posts: 913
Likes: 7
Though I'm not completely read up on the subject, and I'm thinking this would have been mentioned, don't these engine controls have a rev-limiting feature at a certain threshold?
4500 RPM sounds a little high, is it really at that number, and does it happen when actually driving the truck?
4500 RPM sounds a little high, is it really at that number, and does it happen when actually driving the truck?
It will rev freely to that in park.
No codes, water temp stays well in the lower area of "normal" on the gauge (the gauge does function).
Fuel pressure is between 41-37 PSI from idle to WOT.
I havent yet pulled the plugs yet - I'm debating replacing them just to be safe.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
It could be an ignition related misfire but considering all the parts you have on the motor it could also be that it is running a little lean in that area as a result of the SD systems limitations. A wideband O2 would help diagnose that and an adjustable FPR might cure it but it may also be a sign that you are a hair away from needing MAF.
Thread Starter
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Laughing Gas
Joined: Apr 2011
Posts: 913
Likes: 7
It could be an ignition related misfire but considering all the parts you have on the motor it could also be that it is running a little lean in that area as a result of the SD systems limitations. A wideband O2 would help diagnose that and an adjustable FPR might cure it but it may also be a sign that you are a hair away from needing MAF.
I DID keep the original springs, rods, and rockers, and I was wondering if this could possibly be a symptom of valve float or something similar?
I'll have to look around for a wideband O2 sensor, any recommendations there? And I'll try and snag an adjustable FPR. I've been wanting one for years anyways.