laying over above 5000rpms...
04-15-2008, 03:21 AM
#1
laying over above 5000rpms... Need some ideas, I'm having an issue with the car laying over above 5000 rpms.(well, wot is pretty much just above 5000rpm with the 4000 stall, lol)
Quick details of the car...
355, small cam, ported heads
Real Quick's header kit
GTS 76
th400/4000 stall
72lb low impedence injectors with resistor box
stock pcm(obdI) tuned via tuner cats by myself
CLIFFS...
at wot rpms will go up and down then back up again then down....repeat
new coil, new opti, new plug wires, new plugs, new coil wire
One night it ran perfectly strong without doing anything to it, then cut out again...then fixed it for 1/2 a day once by pushing on the coil wire better on the old coil that was corroded, and fixed it for one night another day by replacing the coil, then it went back to laying over.
verified fuel pressure is solid at wot also, not dropping off
Sorry for the novel below, but want all my details out there....
-----------------------------
Ever since putting this car back together it's been down on power, now I can blately feel it laying over above 5000 rpms. Little background...
Got the car running with 4lbs and the transmission immediately started slipping. Even with the slipping transmission I could pull my buddies 115mph 3rd gen on the highway punches. Got the transmission fixed and had a boost creep issue, wouldn't hold solid boost, anywhere from 4lbs to 9lbs with the 4lb spring. I had some 110 gas in it, so we threw in my 8lb spring to see what it would do at about 10pm on a Friday night. We tried a pull with both 255 fuel pumps on and the car went 9.6:1 AFR and cut out. Ended up realizing my 2nd pump was jumping my fuel pressure about 5lbs(stock return line) and causing my AFPR to jump crazy high in pressure.(once it his about 65lbs it just jumps to 80+) So turned it down, got the pressure correct, and we double checked over everything on the car, which I do remember pushing on the coil wire.(you'll see later why this is handy information) Went out and made a few pulls and it pulled exactly 11lbs, and with 14 degrees of timing the car flat out MOVED OUT HARD. Probably 133-135mph, which is what it should do on 11lbs. Went out that night and it started boost creeping on me again, up to 13 or 14, so I was backing out of the throttle. Next day found out the flex cupler collased from the WG back to the downpipe, which caused the boost creep, so I switched to open atmosphere on the wastegate, but didn't make any pulls really since I was back on pump gas, still not having the tune dialed in exactly as I wanted.
Fast forward one week, pulled out the tr6 plugs(gapped at .032) and put in some tr7ix that I had laying around. Went out and at 6lbs it would blow out the spark. Next day, pulled them out and put in some ngk br7ef plugs gapped at .026. Threw in the good gas, and had the 4lb spring in it, so I could tune it from 4 all the way up to 15lbs.
Hit the dyno, car didn't make nearly the power it should. As we turned it up(8lbs up to 15lbs), the shop owner said he could feel it lay over around 5600rpm. The graph was a little wavey up top so I added timing, from 14 to 23(since it had good gas anyway) and it picked up right at 50rwhp at 8lbs. I pulled it back down to 18 degrees, but we didn't make another pull at 8lbs. As we turned it up to 11lbs and up, the afr would go through the floor, 10.0 afr. I kept pulling fuel in the tune, but it would stay 10.0 afr.(even after pulling out over 25% fuel)
Pulled it out on the street, and knew it would be way to lean, went out and on 9lb setting it leaned out immediately. I put the fuel back in it and afr was about 11.2 across the board. Went out and raced it that night and could tell it was just down badly on power, even at 14lbs it pulled WAY less than it did before on 11lbs.
So I started checking over everything and noticed the coil wire(taylor) on the coil wasn't going on completely and clicking like it should. We looked closer at the coil and the post inside was eroded away really bad. Well we FINALLY got it to click on the post. Went out and the car felt a million times better. Back on 8lbs the car pulled strong like it should. Bumped it up to 11lbs and the car moved out hard, but not quite as hard as before, still probably 130mph range.
Later that night the power died off again, I figured the coil wire came loose again and it did. So next day when the parts store opened up I bought a new coil and put on the car. Car felt AMAZING on 8lbs, and great on 13lbs! Didn't cut out at all, and went out racing. Made probably 15 pulls on it, all smooth and perfect.
Next day headed to the track, on the way there got on it and felt it completely lay over like it did before when the coil wire wasn't clicking on the coil. Got to the track, pushed the wire on, but still didn't run any better. I made no changes from the night before, even on the same tank of gas(mix of 110/pump).
So, since then I've been trying to figure this issue out. I've replaced the opti, a few coil wires, few coils(including the huge msd hvc-2 that ponyhunter had to switch to get his miss gone), replaced the plugs(back to the tr6's even), replaced plug wires, hooked up a mallory 685 box. I've tried about everything I can think of, but it still keeps laying over.
Best way to describe what it is doing, is if your spraying a car with a 100 shot and just let off the button around 5000rpms, then maybe tap it again, then let off it.
Sometimes it will make a clean pull though, I went to the track last week and hot lapped it. It made a few low 12 passes on 8lbs, laying over. Then made a great 1/8th mile pass, didn't lay over until the end of the first 1/8th and it went 7.1 at 100mph in the 1/8 and I was backing off the gas to see if it would quit cutting out on the back 1/8th and went 11.12 at 122mph. This is where the 1/8th should be on 8lbs without launching it hard, last year I went 6.9 at 100mph in the 1/8th and 10.80 at 128mph on the back end, which I think it should do on 8lbs this year.
Today, I made some pulls and datalogs will show the rpm going up then BACK DOWN! Timing stays at 18 degrees, afr is FLAT at 11.3.
Example from datamaster...
4125rpm
4925rpm
5425rpm
5025rpm
5350rpm
5075rpm
5125rpm
5325rpm
This was all 3rd gear on a highway pull.
Another one....
4400
5275
5700
5750
5525
5050
5100
This is all while I am still WOT.
Anybody have any ideas, I'm trying to make the ltx shootout, but this has been my problems for the last two weeks, not to mention the rear end I've replaced already, and on my 3rd transmission. This year isn't starting out good.
Quick details of the car...
355, small cam, ported heads
Real Quick's header kit
GTS 76
th400/4000 stall
72lb low impedence injectors with resistor box
stock pcm(obdI) tuned via tuner cats by myself
CLIFFS...
at wot rpms will go up and down then back up again then down....repeat
new coil, new opti, new plug wires, new plugs, new coil wire
One night it ran perfectly strong without doing anything to it, then cut out again...then fixed it for 1/2 a day once by pushing on the coil wire better on the old coil that was corroded, and fixed it for one night another day by replacing the coil, then it went back to laying over.
verified fuel pressure is solid at wot also, not dropping off
Sorry for the novel below, but want all my details out there....
-----------------------------
Ever since putting this car back together it's been down on power, now I can blately feel it laying over above 5000 rpms. Little background...
Got the car running with 4lbs and the transmission immediately started slipping. Even with the slipping transmission I could pull my buddies 115mph 3rd gen on the highway punches. Got the transmission fixed and had a boost creep issue, wouldn't hold solid boost, anywhere from 4lbs to 9lbs with the 4lb spring. I had some 110 gas in it, so we threw in my 8lb spring to see what it would do at about 10pm on a Friday night. We tried a pull with both 255 fuel pumps on and the car went 9.6:1 AFR and cut out. Ended up realizing my 2nd pump was jumping my fuel pressure about 5lbs(stock return line) and causing my AFPR to jump crazy high in pressure.(once it his about 65lbs it just jumps to 80+) So turned it down, got the pressure correct, and we double checked over everything on the car, which I do remember pushing on the coil wire.(you'll see later why this is handy information) Went out and made a few pulls and it pulled exactly 11lbs, and with 14 degrees of timing the car flat out MOVED OUT HARD. Probably 133-135mph, which is what it should do on 11lbs. Went out that night and it started boost creeping on me again, up to 13 or 14, so I was backing out of the throttle. Next day found out the flex cupler collased from the WG back to the downpipe, which caused the boost creep, so I switched to open atmosphere on the wastegate, but didn't make any pulls really since I was back on pump gas, still not having the tune dialed in exactly as I wanted.
Fast forward one week, pulled out the tr6 plugs(gapped at .032) and put in some tr7ix that I had laying around. Went out and at 6lbs it would blow out the spark. Next day, pulled them out and put in some ngk br7ef plugs gapped at .026. Threw in the good gas, and had the 4lb spring in it, so I could tune it from 4 all the way up to 15lbs.
Hit the dyno, car didn't make nearly the power it should. As we turned it up(8lbs up to 15lbs), the shop owner said he could feel it lay over around 5600rpm. The graph was a little wavey up top so I added timing, from 14 to 23(since it had good gas anyway) and it picked up right at 50rwhp at 8lbs. I pulled it back down to 18 degrees, but we didn't make another pull at 8lbs. As we turned it up to 11lbs and up, the afr would go through the floor, 10.0 afr. I kept pulling fuel in the tune, but it would stay 10.0 afr.(even after pulling out over 25% fuel)
Pulled it out on the street, and knew it would be way to lean, went out and on 9lb setting it leaned out immediately. I put the fuel back in it and afr was about 11.2 across the board. Went out and raced it that night and could tell it was just down badly on power, even at 14lbs it pulled WAY less than it did before on 11lbs.
So I started checking over everything and noticed the coil wire(taylor) on the coil wasn't going on completely and clicking like it should. We looked closer at the coil and the post inside was eroded away really bad. Well we FINALLY got it to click on the post. Went out and the car felt a million times better. Back on 8lbs the car pulled strong like it should. Bumped it up to 11lbs and the car moved out hard, but not quite as hard as before, still probably 130mph range.
Later that night the power died off again, I figured the coil wire came loose again and it did. So next day when the parts store opened up I bought a new coil and put on the car. Car felt AMAZING on 8lbs, and great on 13lbs! Didn't cut out at all, and went out racing. Made probably 15 pulls on it, all smooth and perfect.
Next day headed to the track, on the way there got on it and felt it completely lay over like it did before when the coil wire wasn't clicking on the coil. Got to the track, pushed the wire on, but still didn't run any better. I made no changes from the night before, even on the same tank of gas(mix of 110/pump).
So, since then I've been trying to figure this issue out. I've replaced the opti, a few coil wires, few coils(including the huge msd hvc-2 that ponyhunter had to switch to get his miss gone), replaced the plugs(back to the tr6's even), replaced plug wires, hooked up a mallory 685 box. I've tried about everything I can think of, but it still keeps laying over.
Best way to describe what it is doing, is if your spraying a car with a 100 shot and just let off the button around 5000rpms, then maybe tap it again, then let off it.
Sometimes it will make a clean pull though, I went to the track last week and hot lapped it. It made a few low 12 passes on 8lbs, laying over. Then made a great 1/8th mile pass, didn't lay over until the end of the first 1/8th and it went 7.1 at 100mph in the 1/8 and I was backing off the gas to see if it would quit cutting out on the back 1/8th and went 11.12 at 122mph. This is where the 1/8th should be on 8lbs without launching it hard, last year I went 6.9 at 100mph in the 1/8th and 10.80 at 128mph on the back end, which I think it should do on 8lbs this year.
Today, I made some pulls and datalogs will show the rpm going up then BACK DOWN! Timing stays at 18 degrees, afr is FLAT at 11.3.
Example from datamaster...
4125rpm
4925rpm
5425rpm
5025rpm
5350rpm
5075rpm
5125rpm
5325rpm
This was all 3rd gear on a highway pull.
Another one....
4400
5275
5700
5750
5525
5050
5100
This is all while I am still WOT.
Anybody have any ideas, I'm trying to make the ltx shootout, but this has been my problems for the last two weeks, not to mention the rear end I've replaced already, and on my 3rd transmission.
This year isn't starting out good. Last edited by skinnies; 04-15-2008 at 03:35 AM.
04-17-2008, 04:20 AM
#2
Did a lot today, didn't get anywhere though. Looks like I'm out for the ltx shootout, which really sucks, been building this car all winter to drive to the shootout, click off a high 9 on 17" radials, and drive home.
I rerouted all the wires to the top of the intake, checked every single wire carefully and ohm tested all of them. I wrapped them all seperately and shielded them from each other, still cuts out. Also checked the pins on the opti harness and tried a new opti harness also.
New ICM and still does it.
I did find out it does it WORSE with the ignition box hooked up, which reminds me it did also do it worse with the msd hvc-2 coil. This makes me really think its a misfire issue.
Also the car seems to spool A LOT faster cruising around, which makes me think maybe it is cutting out all the time and is just barely doing it so I don't notice it.
Timing is 18-19 degrees dead locked in at WOT.
I'll pull off the valve covers again tomorrow and check the lash on the valves, but I don't think this is the issue since changing the coil before FIXED the problem for a day.
I rerouted all the wires to the top of the intake, checked every single wire carefully and ohm tested all of them. I wrapped them all seperately and shielded them from each other, still cuts out. Also checked the pins on the opti harness and tried a new opti harness also.
New ICM and still does it.
I did find out it does it WORSE with the ignition box hooked up, which reminds me it did also do it worse with the msd hvc-2 coil. This makes me really think its a misfire issue.
Also the car seems to spool A LOT faster cruising around, which makes me think maybe it is cutting out all the time and is just barely doing it so I don't notice it.
Timing is 18-19 degrees dead locked in at WOT.
I'll pull off the valve covers again tomorrow and check the lash on the valves, but I don't think this is the issue since changing the coil before FIXED the problem for a day.
