Like the title says Im having some trouble here. I just put new heads on and rebuilt the TBI 6 monthes ago. But for some reason all of the sudden the engine runs like there is a flat spot in it similar to a carb. I sprayed everything down with carb cleaner and water and couldn't find a vacume leak. It idles perfect but from like 1/4 throttle to 3/4 throttle it just sputters and wants to die, but once you hammer it and it gets some fuel it takes off like nothing is wrong. This problem also seams to go away after the engine has been hot for a while, like 200. It also is not setting any hard codes. I had a check light come on a couple weeks ago but it didn't store and I didn't have my scanner on me. The only thing I have done since the rebuild is install a MSD 6A box but I think the box was toast because everything was running like crap, wasn't idleing right, so I pulled it. I want to think it is a vacume leak or gasket somewhere because it goes away when it is warmed up for a while. But it happend after I installed the MSD box so I guess it could be a sensor somewhere. Does anyone have any input?

Mike

throttle position sensor maybe taking a dump?

Maybe have a look at your egr may be sucking up will cause the problems you are having. But I can't see y the temp would affect the Egr

Check the codes and see if your pulling one. The TPS won't pull a code, but I really don't think thats what it is. Check your fuel pressure? And don't discount a bad injector? Change the fuel filter? Check codes first...

You know, EGR would make it idle poor, and without proper TPS signal it would'nt know you've got it to the floor. Another thing is to make sure it's in closed loop. The leading cause of no closed loop is O2 sensor...

did the heads change the compresion? it takes out somewhere around 8 degrees when it detects knock. Did you disconnect that brown wire when you set the base timing?

I think the map sensor would cause more of this problem than a tps. Is it hooked up to the back of the throttle body? is every vacuum port plugged?

The timing is set right, the EGR and O2 sensor are new from trying to get this thing to smog, the vacume ports seem to be all plugged. I just replaced the TPS a year ago when I was getting a code for it then, but it could definatly have gone bad, I have no idea what the MAP sensor is but I'll get out my book and check it. And I don't have a code scanner just one of those things that flashes the light, so if anyone around Chico has a scanner I would love to see if any are stored. I had my mechanic check it with his Snapon Scanner when this first started happening and he said there were none stored. The compression is good before the head swap and is still in the green now, and the fuel filter is newer, but im gonna change it again. Would an injector go bad that fast and would these be the symptoms?

Thanks for all the fast input I allready had this thing blow a 10 bolt in Tahoe last winter so I replaced it with a FF disc 14 bolt. I am trying to get a relyable ski trip, snow wheelin rig on a poor graduate student bank roll.

Mike

Map sensor is black and is about 2"x4" with a vacuum hose going to it. I had an injector go bad and I can tell you that it doesn't set a code.

Is there anyway to see if the MAP or injector is bad? I know you can test the TPS with a snapon type scanner what about the MAP or injector, is that something I can test or do I just replace and see?

Mike

Do a search for "Fuel Injection diagnostics flow chart". This has worked for me a time or two.