Help Me Out With Some Problems...Heads/Cam Car
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Registered User
Joined: Sep 2001
Posts: 175
From: Cullman,AL
Help Me Out With Some Problems...Heads/Cam Car
Ok, several of you guys have probably seen a few of my posts regarding my new combo, but here it is in detail:
1994 Z28, M6
Lloyd Elliott Ported Heads with .600 Springs, 2.02/1.60 valves
227/233, 560/569 Comp XE Cam
1.6 Comp Pro Mag RR's, Non Self Aligning/Guideplates
Jet Hot Longtubes with Hooker Y-Pipe
Moroso CAI
MSD 6A
SVO 30lb Injectors
AIR and EGR Deleted
Madwolf Mail Order PCM Tune
Ok, I need some input or advice about some problems that I am having. The car idles nicely at around 900rpm and pulls good at most times. Sometimes the car has a decent amount of surge under light acceleration, but thats understandable. However, at highway speeds of 55-60 it sometimes has some surge or vibration. Also, the dyno numbers were low at 351hp/332tq. The car feels very strong on the street at WOT though. The AF ratio showed 14.0-14.1 on the wideband across the entire dyno sheet. Keep in mind I do not have some of the bolt on type mods like a underdrive pulley, air foil or an aftermarket catback exhaust system on the car. It just has a flowmaster in the stock rear section so I am probably losing some power there. One more thing that worries me is that my car only pulls to 6200rpm, THATS IT. After 6200 it just fall on its face. I know it shouldn't do that. What I need is some advice from you guys about what I should do. I have talked with Ion(madwolf) and he tells me that his tune should not be that lean and I have no reason to doubt him. Is there anything that could be causing my lean condition and early rpm crapout along with the other problems? I am really stumped on this and need some input. Maybe some false knock? Or a degrading Opti? I really have no idea where to start.
1994 Z28, M6
Lloyd Elliott Ported Heads with .600 Springs, 2.02/1.60 valves
227/233, 560/569 Comp XE Cam
1.6 Comp Pro Mag RR's, Non Self Aligning/Guideplates
Jet Hot Longtubes with Hooker Y-Pipe
Moroso CAI
MSD 6A
SVO 30lb Injectors
AIR and EGR Deleted
Madwolf Mail Order PCM Tune
Ok, I need some input or advice about some problems that I am having. The car idles nicely at around 900rpm and pulls good at most times. Sometimes the car has a decent amount of surge under light acceleration, but thats understandable. However, at highway speeds of 55-60 it sometimes has some surge or vibration. Also, the dyno numbers were low at 351hp/332tq. The car feels very strong on the street at WOT though. The AF ratio showed 14.0-14.1 on the wideband across the entire dyno sheet. Keep in mind I do not have some of the bolt on type mods like a underdrive pulley, air foil or an aftermarket catback exhaust system on the car. It just has a flowmaster in the stock rear section so I am probably losing some power there. One more thing that worries me is that my car only pulls to 6200rpm, THATS IT. After 6200 it just fall on its face. I know it shouldn't do that. What I need is some advice from you guys about what I should do. I have talked with Ion(madwolf) and he tells me that his tune should not be that lean and I have no reason to doubt him. Is there anything that could be causing my lean condition and early rpm crapout along with the other problems? I am really stumped on this and need some input. Maybe some false knock? Or a degrading Opti? I really have no idea where to start.
Last edited by whontime; Dec 4, 2003 at 04:26 PM.
Registered User
Joined: Apr 2001
Posts: 557
From: KU
I agree with Madwolf that seems pretty lean. I don't have personal experience with him but usually mail order tunes are a little on the rich side if anything. IMHO I would get the TTS data master scan tool. Go ahead and run it and then send the info. to Madwolf. He should be able to let you know exactly what is happening.
Registered User
Joined: May 2003
Posts: 2,275
KC's right, just send the data. I did notice a couple of things and wanted to ask a question. You already mentioned you have a pretty much stock exhaust and I assume a stock (read old and clogged) cat convertor. I have also heard (I'm not getting into this stupid debate) that flowmasters can be restrictive. Obviously your stock system is restrictive. This will contribute to falling flat on it's face. I also noticed that you have the stock TB. A larger TB would help as long as you uncork the exhaust. None of this however explains if you are running lean or not. Perhaps there is some sort of input problem from the O2s or other sensors to the PCM. A scan may help in that regard.
With regards to falling flat on it's face. I'm wondering about the valves or lifters with regard to over 500 lift at 6200 RPMs. First I didn't see where you changed the lifters. Obviously high spring pressure and high lift agravated with fast ramps can contribute to meager OEM lifters colapsing. Second, XE cams have fast opening ramps. Since I'm not an expert with Comp cams, it could be your experiencing valve float. Remember 6500 rpms is only a guideline. Although colapsing lifters are more likely than valve float. The question is, are the duration numbers advertised or at .050 and I assume the lift numbers you provided are after having multiplied by 1.6. meaning true lift at the cam is 350/356.
The last thing to consider is the push rods rubbing on the heads. I've read a lot people having that problem and the symptom does exactly what you said.
Stock heads with a high rocker ratio are prone to touching.
With regards to falling flat on it's face. I'm wondering about the valves or lifters with regard to over 500 lift at 6200 RPMs. First I didn't see where you changed the lifters. Obviously high spring pressure and high lift agravated with fast ramps can contribute to meager OEM lifters colapsing. Second, XE cams have fast opening ramps. Since I'm not an expert with Comp cams, it could be your experiencing valve float. Remember 6500 rpms is only a guideline. Although colapsing lifters are more likely than valve float. The question is, are the duration numbers advertised or at .050 and I assume the lift numbers you provided are after having multiplied by 1.6. meaning true lift at the cam is 350/356.
The last thing to consider is the push rods rubbing on the heads. I've read a lot people having that problem and the symptom does exactly what you said.
Stock heads with a high rocker ratio are prone to touching.
Thread Starter
Registered User
Joined: Sep 2001
Posts: 175
From: Cullman,AL
Originally posted by slopokrodrigez
KC's right, just send the data. I did notice a couple of things and wanted to ask a question. You already mentioned you have a pretty much stock exhaust and I assume a stock (read old and clogged) cat convertor. I have also heard (I'm not getting into this stupid debate) that flowmasters can be restrictive. Obviously your stock system is restrictive. This will contribute to falling flat on it's face. I also noticed that you have the stock TB. A larger TB would help as long as you uncork the exhaust. None of this however explains if you are running lean or not. Perhaps there is some sort of input problem from the O2s or other sensors to the PCM. A scan may help in that regard.
With regards to falling flat on it's face. I'm wondering about the valves or lifters with regard to over 500 lift at 6200 RPMs. First I didn't see where you changed the lifters. Obviously high spring pressure and high lift agravated with fast ramps can contribute to meager OEM lifters colapsing. Second, XE cams have fast opening ramps. Since I'm not an expert with Comp cams, it could be your experiencing valve float. Remember 6500 rpms is only a guideline. Although colapsing lifters are more likely than valve float. The question is, are the duration numbers advertised or at .050 and I assume the lift numbers you provided are after having multiplied by 1.6. meaning true lift at the cam is 350/356.
The last thing to consider is the push rods rubbing on the heads. I've read a lot people having that problem and the symptom does exactly what you said.
Stock heads with a high rocker ratio are prone to touching.
KC's right, just send the data. I did notice a couple of things and wanted to ask a question. You already mentioned you have a pretty much stock exhaust and I assume a stock (read old and clogged) cat convertor. I have also heard (I'm not getting into this stupid debate) that flowmasters can be restrictive. Obviously your stock system is restrictive. This will contribute to falling flat on it's face. I also noticed that you have the stock TB. A larger TB would help as long as you uncork the exhaust. None of this however explains if you are running lean or not. Perhaps there is some sort of input problem from the O2s or other sensors to the PCM. A scan may help in that regard.
With regards to falling flat on it's face. I'm wondering about the valves or lifters with regard to over 500 lift at 6200 RPMs. First I didn't see where you changed the lifters. Obviously high spring pressure and high lift agravated with fast ramps can contribute to meager OEM lifters colapsing. Second, XE cams have fast opening ramps. Since I'm not an expert with Comp cams, it could be your experiencing valve float. Remember 6500 rpms is only a guideline. Although colapsing lifters are more likely than valve float. The question is, are the duration numbers advertised or at .050 and I assume the lift numbers you provided are after having multiplied by 1.6. meaning true lift at the cam is 350/356.
The last thing to consider is the push rods rubbing on the heads. I've read a lot people having that problem and the symptom does exactly what you said.
Stock heads with a high rocker ratio are prone to touching.
Registered User
Joined: May 2003
Posts: 2,275
Lifters got to go. While you're there, check the pushrods to see that they don't contact the heads.
As far as the TB is concerned, now that you're using the 202/160's and the larger lift you have to let that combo breath better with a 52mm TB. sure there are knuckleheads out there that think that just changing the TB with nothing else will do something. You're combo of heads and cam however require more.
I see nothing stock about your exhaust at all. LT's with a new Y pipe and the cat is gone. Nothing at all restrictive about that.
If your enrichment tables are programmed correctly, I would have to think your PCM is not seeing how much air is entering the engine and therefore not richening it up enough. If you checked the MAF, TPS and MAP sensors, then a quick scan of the O2's is in order.
By the way, what is your vacuum level?
As far as the TB is concerned, now that you're using the 202/160's and the larger lift you have to let that combo breath better with a 52mm TB. sure there are knuckleheads out there that think that just changing the TB with nothing else will do something. You're combo of heads and cam however require more.
I see nothing stock about your exhaust at all. LT's with a new Y pipe and the cat is gone. Nothing at all restrictive about that.
If your enrichment tables are programmed correctly, I would have to think your PCM is not seeing how much air is entering the engine and therefore not richening it up enough. If you checked the MAF, TPS and MAP sensors, then a quick scan of the O2's is in order.
By the way, what is your vacuum level?
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