Fired up the car for the first time after head/cam/headers install...Car dies at idle after warm up and runs erratically & rough..

Is this due to the fact that it just needs to be tuned???

Car is a 98 with manual tranny and was all stock engine before i got ahold of it.

Here's the mods done:
1. LS1 heads ported & milled .050
2. Comp cams XR275HR cam (222/224 - .566/.568 w 1.7 rocker - 112 LSA)
3. LS6 intake
4. catch can
5. complete new valvetrain (rockers,pushrods, springs etc.)
6. new plugs & wires.
7. removed AIR system
8. removed cats & rear 02 sensors

no check engine codes yet....(drove it for about 5 minutes)

thanks for any input...I am taking it to the tuner on monday or tuesday.

 

Could be the tune. Which rockers did you install and did you check lifter preload and rocker wipe pattern?

 

It will probably need a tune after those mods. I would also double check that all vacuum hoses are connected up and check that you don't have a vacuum leak anywhere.

 

You're going to need a tune but as soon as you finish reading this post, go measure preload, be sure the springs aren't binding, check the wipe pattern, and do all this turning the engine over without starting it. Enough things have been changed that it is not automatic that everything has the clearance it needs. For giggles and grins, take the push rods and roll them on a piece of plate glass. I REALLY hope they will roll. If any one of them doesn't, you'll probably want to take a look at the cam lobes and lifter rollers.

Charlie

 

You really need to tune the auto after all of the mods. You still have the stock tune in the car and it trying to act as though you have stock air flow and a cam with number like 207 213 487 485 LSA 117.5 and IDLe of 600 and AFR around 10-10.6 or so. Now with all that you have did, wouldn't you run rough too?

 

Went with the yella rockers...yes i did the wipe pattern check after i was done with everything..its perfectly centered...

I used a comp cams pushrod length checker to get the correct pushrod length.

i also did ptv clearance and fly cut my pistons .035 for the minimum clearance of .080 on the intake. I used the dial indicator (weak springs) method to find my clearance.

checked all hoses & electrical connectors twice before firing it up..everything is connected...

So that said...think it could be just the tuning?????

 

I am in the same boat... Hope you find the resolution.

 

If everything checks then the tune should straighten it out. I have a much milder cam and when first installed it did some hunting whenever I stopped. The tune took care of it, part of which is a slight increase in idle speed. Don't forget to post your dyno curve

 

Idle problems, you should have. It shouldnt really run "rough" though.
You may want to check your plugs and plug wires. Make sure you dont have a cracked plug, and all the plug wires are snappedon the coils and plugs real good.

 

Sounds like you left the ground wire off the back of the left cylinder head

 

Yowzah! With the clearance issue out of the way, it sounds like a tune is all you need to do. It may be that driving the car for 30 - 40 miles to let the ECM re-learn will help a bunch and the tune will pull everything in synch.

Charlie

 

Didn't even think about the ground strap, but it is easy to leave off. Even if it's there, check both ends for clean connections.

Charlie

 

I bolted the grounding eye to the drivers side head...I got that one...I even went so far as to rebolt the wiring harness to the passenger side head..I have no hoses loose or disconnected..

brake booster...check
tiny vacuum hose at back of intake..check
pcv system...check
map sensor electrical at back of intake mani....check

I installed new plugs (factory) & plug wires & installed the plugs when the heads were off the car...

I really cant think of anything else that it could be..

when i was driving it yesterday (only about 3-4 minutes) and holding a steady throttle position, the car was surging at about 2000 rpm...i decided not to go past 2500 rpm since it was running like that...

once again..thanks for all your help with this...

 

I dont think it would start at all with the ground strap off. Sounds like its a tuning problem. The idling and dying is the IAC, its set for your stock heads and cam and cannot compensate. The thing will learn a little, but the tune will take care of it. Put a few miles on it, let it cool down. Put a few more miles on it, then let it cool down. Heat cycle it a few times (up to full operating temp, then park it for a few hours) and then you should be good to go get a tune.

 

Will do..I'll try that later today...

thanks Mike

 

Anytime... the heat cycling will not really help your car learn the tune, it will however break your valve springs in so whoever tunes your car can get on it without risking breaking one

 

From your first post, you mention that it dies after warm-up...if this is the case, I'm presuming that it runs fine for a while until it warms up. If this is true, you may want to check your O2s and check for any air leaks.

When you first start the car it should be running in OL for 120 seconds or until it hits a temp preset, plus 120 seconds. Sounds like when your car goes into CL the PCM is adjusting the fueling and subsequently killing the car.

Mine did this due to a bad O2 reading rich, PCM kept pulling fuel until the car was virtually undriveable.

 

I had a similar issue. My problem was with the MSD wires. The extra heat from the h/c melted the wires. Went back to stock wires with heat shields and it fixed the issue. A tune also helped quite a bit.

 

Well, i got the car back from the tuners here in town...the car definitely has something wrong that's not tuning related....

Here's the symptoms/problems..When the car is in open loop operation (engine temp below 140F at startup), everything runs normal...As soon as it heats up and goes into closed loop, it runs like crap (surges & hesitates) at idle & low throttle positions..

changing the throttle position rapidly to 40-50% (strictly guessing) makes it run normal like it should, until you let off the throttle again...It seems like after driving for 20 minutes or so and the problem goes away also....until next time you start it...

ok..lets get to the codes...the only one is P0171 (bank 1 lean code) but i know its definitely not running lean because it is blowing black smoke & black fluid droplets out of the tailpipe..(no cats or mufflers)

I thought the 02 sensor might be the problem, so i swapped them from left to right & vice versa...still the same black smoke out of the drivers side pipes & the same P0171 code.

If there were a vacuum leak in the intake manifold, both sides would be affected...

If there was a leak from left side injector o-ring or intake manifold gasket, this would cause a lean condition, but it should burn all the fuel right??? and not blow black smoke??

Any guesses on what this could be?

 

anyone?