High RPM miss
07-04-2010, 09:33 PM
#1
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High RPM miss I recently completed a '05 5.3L swap into my 68 C-10. It was running fine until a fews days ago.
I got on it and it started missing at high rpms (>4500 rpms). So then I made a log of it. I don't have a whole lot of experience with HPtuner and diagnosing stuff, but in my log file I didn't see much that concerned me. I'm not getting any DTCs either.
So in the attached log file, I got on it a few times, and each time it would miss and do the same thing. There isn't any knock retard or anything else. The only thing that I see that seems odd is when I'd let off the gas, the timing advance would go negative.
Under normal driving conditions, it is doing fine.
Is there something else I should log to help diagnose this?
I got on it and it started missing at high rpms (>4500 rpms). So then I made a log of it. I don't have a whole lot of experience with HPtuner and diagnosing stuff, but in my log file I didn't see much that concerned me. I'm not getting any DTCs either.
So in the attached log file, I got on it a few times, and each time it would miss and do the same thing. There isn't any knock retard or anything else. The only thing that I see that seems odd is when I'd let off the gas, the timing advance would go negative.
Under normal driving conditions, it is doing fine.
Is there something else I should log to help diagnose this?
07-04-2010, 10:23 PM
#2
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assuming you have everything hooked up and good I would look from your pickup tube up to your fuel rail. (fuel filter strianer) those old tanks usually have rust in them or they usually do when I mess with them you would normally just pull the copper filter out of the carb and beat the trash out. what about your line, any kinks, what did you do for a return line? Are you running a inline pump or in tank pump? You need to check fuel pressure during the miss. I swapped a tpi into an older truck and my inline pump was causing a similiar problem because my lines were pinched.
07-04-2010, 10:37 PM
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I'm using a fuel tank and pump from a 2000 T/A with a corvette fuel pressure regulator/filter. From there the fuel line runs all the way up to the engine (short return line from the fpr/f back to the tank.
I guess maybe this will motivate me to get my wideband hooked up.
I guess maybe this will motivate me to get my wideband hooked up.
07-05-2010, 09:58 AM
#5
How fresh are your plugs and wires?
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
07-05-2010, 11:11 AM
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ya know, now that I think about it, I recently filled it up after my first full tank of gas (until yesterday I had 400 miles on the setup) and so maybe once the tank got down to the bottom, it got some trash sucked up into it. Also, like I said it just started happening (if I remember right about the time I filled up)
The wires are original, with about 75k on them, but that should not be a problem. I can't remember if I changed the spark plugs before installing the engine...pretty sure I did.
The wires are original, with about 75k on them, but that should not be a problem. I can't remember if I changed the spark plugs before installing the engine...pretty sure I did.
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07-23-2010, 08:24 PM
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After reading another post on the same subject, I made up a new spark plug wire with a 90 degree boot (#3 cylinder) on it rather than straight and re-routing the wire so it didn't touch the header. Looks like this took care of the problem. Several full throttle runs up to ~70 with no problems.
07-08-2011, 11:38 AM
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TTT
I thought I had the problem fixed, but now it is still doing it. Same problem.
I only have 800 miles on the truck, so I haven't driven it much since the original post, and I've moved twice....so I haven't had much chance to work on the problem.
I'm thinking I'll change the spark plugs. I've read on other boards about bad plugs (brand new ones) so maybe thats the problem. I have some new NGKs and Bosch Platinums sitting on the shelf at home.
Any other ideas?
I thought I had the problem fixed, but now it is still doing it. Same problem.
I only have 800 miles on the truck, so I haven't driven it much since the original post, and I've moved twice....so I haven't had much chance to work on the problem.
I'm thinking I'll change the spark plugs. I've read on other boards about bad plugs (brand new ones) so maybe thats the problem. I have some new NGKs and Bosch Platinums sitting on the shelf at home.
Any other ideas?
07-09-2011, 12:10 AM
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Well I changed the spark plugs to some NGKs (TR5GP @ .040)
But anyways, of the ones I pulled out, 7 were ACdelco PN 12567759 / NGK PZTR5A gapped at .060
The eighth one is a Bosch platinum plus gapped at ~.038. Kinda brings back memories that maybe I broke one of the original ones (AC delco) at some point in the build process of my truck, so I changed that one spark plug with the bosch, and had the other 7 boschs sitting on a shelf.
I didn't get a chance to drive the truck since its late.
But anyways, of the ones I pulled out, 7 were ACdelco PN 12567759 / NGK PZTR5A gapped at .060
The eighth one is a Bosch platinum plus gapped at ~.038. Kinda brings back memories that maybe I broke one of the original ones (AC delco) at some point in the build process of my truck, so I changed that one spark plug with the bosch, and had the other 7 boschs sitting on a shelf.
I didn't get a chance to drive the truck since its late.
07-09-2011, 03:41 PM
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Took it out for a test drive and kinda slowly gave it more and more gas with each "pass". Finally I made several test through first and second gear up to about 5500 rpms where its shifting with now issues. So it appears the problem is solved (of course I thought that with the spark plugs too).
Thanks guys!
Thanks guys!
07-11-2011, 09:05 PM
#18
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When you said you had NGKs and Bosch, I was about to say "not the Bosch!". This is the exact reason I stay away from Bosch platinum and champion plugs. Just seen too many problems with them.
