large cam on stock cubes, got some problems
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
large cam on stock cubes, got some problems
I just got finished installing a Combinations Motorsports TN-236XL cam in a .030 over LT1 with Speed Pro PowerForged pistons. I got a tune from Ion and have his assurance that its a good tune, which I'm not worried about. However I've got serious driveability issues.
Complete mod list:
Speed Pro PowerForged pistons, 11:1 CR, 4.030
TN-236XL cam
Proform 1.6 rockers
Cloyes Double Roller timing set, straight up
CSR Electric waterpump
B&M 58mm TB
SVO 30# injectors
New Opti (rebuilt)
LT4 KM
Hedman Shorties with exhaust leak at the moment
At idle, I'm getting around 75 kPa on the MAP, jumpy idle at between 900-1000 and only because I bumped the throttle screw out some. At idle the IAC is maxed at 160 and if I move the set screw back to original position it tries to idle at about 600 rpm. I'm getting a High MAP code as well. If I try to drive, whenever I pull up at a stop it goes back to the 600 rpm idle unless I keep my foot in it a little. Never goes closed loop.
Just found out looking at my datalog that my left O2 is out. Actually, they both may be, left one likes 4 mV, right one hangs out around 448 most of the time
however the left one is active at idle, right one is not. But, I'm not getting any trouble codes for them. Guess I'll pick up 2 new ones on Friday.
I guess tomorrow I'll put the timing cover back off and double check the timing set and that the opti was located on the pin correctly. I don't have a cam card for the cam (bought it used) so can't really degree it. But everything I'm looking at so far points me towards timing unless someone else has ideas.
Complete mod list:
Speed Pro PowerForged pistons, 11:1 CR, 4.030
TN-236XL cam
Proform 1.6 rockers
Cloyes Double Roller timing set, straight up
CSR Electric waterpump
B&M 58mm TB
SVO 30# injectors
New Opti (rebuilt)
LT4 KM
Hedman Shorties with exhaust leak at the moment
At idle, I'm getting around 75 kPa on the MAP, jumpy idle at between 900-1000 and only because I bumped the throttle screw out some. At idle the IAC is maxed at 160 and if I move the set screw back to original position it tries to idle at about 600 rpm. I'm getting a High MAP code as well. If I try to drive, whenever I pull up at a stop it goes back to the 600 rpm idle unless I keep my foot in it a little. Never goes closed loop.
Just found out looking at my datalog that my left O2 is out. Actually, they both may be, left one likes 4 mV, right one hangs out around 448 most of the time
however the left one is active at idle, right one is not. But, I'm not getting any trouble codes for them. Guess I'll pick up 2 new ones on Friday.I guess tomorrow I'll put the timing cover back off and double check the timing set and that the opti was located on the pin correctly. I don't have a cam card for the cam (bought it used) so can't really degree it. But everything I'm looking at so far points me towards timing unless someone else has ideas.
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: large cam on stock cubes, got some problems
I got the tune from MadZ28 and he says the tune is good, used it on a couple of other cars tuned on the dyno. I think my problems are mechanical.
Registered User
Joined: Apr 2000
Posts: 1,614
From: Charlotte, NC
Re: large cam on stock cubes, got some problems
Sounds like you need to fix this before tearing anything apart.
Just found out looking at my datalog that my left O2 is out. Actually, they both may be, left one likes 4 mV, right one hangs out around 448 most of the time however the left one is active at idle, right one is not. But, I'm not getting any trouble codes for them. Guess I'll pick up 2 new ones on Friday.
Registered User
Joined: Feb 2004
Posts: 2,182
From: Moore OK
Re: large cam on stock cubes, got some problems
Originally Posted by 92LT1RS
New Opti (rebuilt)
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: large cam on stock cubes, got some problems
Originally Posted by Alvin@pcmforless.com
Sounds like you need to fix this before tearing anything apart.
would running excessively rich kill the O2's? they were both working just fine before I started the cam swap, so something took them out since I've been running it afterwards. And the fact both of them don't seem to be working points to something lately that caused it. It won't even run good in Open Loop so something else is going on here, thats why I'm not *too* concerned about them at the moment.
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: large cam on stock cubes, got some problems
Originally Posted by jsetzer
What do you mean buy rebuilt? I know everyone points to opti, but I don't trust anything but a new gm. Perhaps the msd one coming out.
got "new" baseplate and cap/rotor from O'Reilly's. Local GM dealer wanted $400 for a brand new Opti
I didn't want to wait to have one shipped to me from Jason. Originally I was only planning on replacing the baseplate because my bearings were going out. Once I got the cap off I found out I needed a new rotor and cap as well.
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: large cam on stock cubes, got some problems
ok so I put new intake gaskets in, no change.
pulled the Opti off and I *think* it was in the right place. It spun some when I pulled it off so it may have been located wrong. not sure if thats possible though since I set the dowel pin to the correct length.
timing set is dead on. Its the 3 position Cloyes set and I've got it on stock timing.
also, checked the datalog from earlier and the left O2 seems to be fluctuating normally at idle. right O2 is dead it seems. I had to splice in some new wire while I had the engine was out because the bundle had gotten up against the header and almost melted through some of them. not sure if this is causing the problem or not.
if it still runs bad tomorrow when I got back together with it, I'm at a loss.
facts as it sits now:
-no knock at idle
-about 8" of vacuum at idle
-IAC at 160 no matter what, starts out below 100 and slowly comes up, but idle speed doesn't change....?
-pulled 2 of the spark plugs, a little black around the base, tip of the ground strap was white, part of the ceramic around the electrode was white, everything else just like it had a little oil on it
-Opti is a rebuilt unit, all new parts
pulled the Opti off and I *think* it was in the right place. It spun some when I pulled it off so it may have been located wrong. not sure if thats possible though since I set the dowel pin to the correct length.
timing set is dead on. Its the 3 position Cloyes set and I've got it on stock timing.
also, checked the datalog from earlier and the left O2 seems to be fluctuating normally at idle. right O2 is dead it seems. I had to splice in some new wire while I had the engine was out because the bundle had gotten up against the header and almost melted through some of them. not sure if this is causing the problem or not.
if it still runs bad tomorrow when I got back together with it, I'm at a loss.
facts as it sits now:
-no knock at idle
-about 8" of vacuum at idle
-IAC at 160 no matter what, starts out below 100 and slowly comes up, but idle speed doesn't change....?
-pulled 2 of the spark plugs, a little black around the base, tip of the ground strap was white, part of the ceramic around the electrode was white, everything else just like it had a little oil on it
-Opti is a rebuilt unit, all new parts
Registered User
Joined: Jan 2001
Posts: 473
From: New Berlin Wi
Re: large cam on stock cubes, got some problems
Tristin
I had some simular problems when I went from my hot cam to m LE2. I also had a tune from Ion. My problems may not be the same as yours but maybe what I found can help you. My car was having problems idleing when I came up to a stop sign. It would idle fine when I started it but after it warmed up and I was driving the idle would drop like a rock when I pushed in the clutch and slowed down. it would godown to 550rpm and almost die. after a few seconds the stepper motor would take over and it would idle up. THe idle would continue to bounce around under the preset 950 rpms. I also had a map high and a tps high.
The map high was traced to a vacuum leak by the charcoal canister. I fixed that. so that went away, next I found that my throttle was opening past 100 percent (my throttle stop was missing) this was causing the tps high. it was reading 15 percent at wot. I fixed the throttle cable and now that problem is taken care of. Next I messed with the iac/vs/mph table in the ecm. that didn't do anything. I finally removed the throttle body. I have a 52mm borred out stock tb with an airfoil that I bought used. I had never removed the air foil before. I removed it and found that the air bleed hoe between the throttle blades had been plugged with epoxy. I removed the epoxy and drilled out the hole a couple of sizes bigger. The car idles fine under all conditions.
I didn't have any 02 problems, but when I used to work as a tech I did work on a couple of cars that had driveability problems that ended up being solved with new 02s.
I know that these problems are not all the same as yours, I hope that this helps you find the problem. I have found that sometimes we (thirdgen motor swap guys) have to look a little deaper that some of the other guys on these boards. some of the problems I have had have been traced back to things that have to do with the motor swap and not the mods. This may not be your case but It might not hurt to check it out.
I hope this helps a little.
Kory
I had some simular problems when I went from my hot cam to m LE2. I also had a tune from Ion. My problems may not be the same as yours but maybe what I found can help you. My car was having problems idleing when I came up to a stop sign. It would idle fine when I started it but after it warmed up and I was driving the idle would drop like a rock when I pushed in the clutch and slowed down. it would godown to 550rpm and almost die. after a few seconds the stepper motor would take over and it would idle up. THe idle would continue to bounce around under the preset 950 rpms. I also had a map high and a tps high.
The map high was traced to a vacuum leak by the charcoal canister. I fixed that. so that went away, next I found that my throttle was opening past 100 percent (my throttle stop was missing) this was causing the tps high. it was reading 15 percent at wot. I fixed the throttle cable and now that problem is taken care of. Next I messed with the iac/vs/mph table in the ecm. that didn't do anything. I finally removed the throttle body. I have a 52mm borred out stock tb with an airfoil that I bought used. I had never removed the air foil before. I removed it and found that the air bleed hoe between the throttle blades had been plugged with epoxy. I removed the epoxy and drilled out the hole a couple of sizes bigger. The car idles fine under all conditions.
I didn't have any 02 problems, but when I used to work as a tech I did work on a couple of cars that had driveability problems that ended up being solved with new 02s.
I know that these problems are not all the same as yours, I hope that this helps you find the problem. I have found that sometimes we (thirdgen motor swap guys) have to look a little deaper that some of the other guys on these boards. some of the problems I have had have been traced back to things that have to do with the motor swap and not the mods. This may not be your case but It might not hurt to check it out.
I hope this helps a little.
Kory
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: large cam on stock cubes, got some problems
Kory - thanks for the post. the first part of yours sounds exactly like what mine is doing, but I have a rather new BBK 58mm TB on that I ran for a few months on the old setup and it ran fine. Also, I checked the TPS on my datalogs and it looked fine. I'll keep looking around though.
gex - I'll recheck the valves, but I'm fairly sure they are close enough to not be causing big problems like this
gex - I'll recheck the valves, but I'm fairly sure they are close enough to not be causing big problems like this
Thread Starter
Registered User
Joined: Dec 2001
Posts: 426
From: Slidell, LA
Re: large cam on stock cubes, got some problems
idle is about .8V showing 0.0%, haven't checked WOT yet. will do that as soon as I get it ready to fire it again, I'll just turn the key on and check WOT.
