94' K1500 headers installed runs like crap now
 

Hey guys new here, i have been searching all over the net for the past 3 days on some help with my problem and I am to the point of either shooting the truck with as many rifles as i can get my hands on until it looks like swiss cheese or beating my head against a wall.

I have spent much time and effort in building this truck up from a hardly running heap into the truck it is now until 3 days ago when i changed out the manifold for headers.

So i installed new headers, drop in new E3 spark plugs, installed new o2 sensor in the headers bung, and kept my K&N filter. Also another note the cat was removed prior to the headers and it ran just fine so it is going from the y-pipe straight off onto a 2 stage flow master muffler.

Now when i installed the headers i found out that the smog pump/secondary air injection system had to go, no where to plug it in and relatively useless i know, since in the state i live in we do not have emission checks im clear to leave it off.

The problem is that the system seems to hate the headers. Scratching my head it looks to be that the O2 sensor is now reading a higher voltage because the SAI is not longer forcing O2 down the exhaust up stream from the only O2 sensor this truck has (its an OBD-1). So the ECU i think is thinking the engine is running super rich and is leaning it out. Now it sounds to run fine at idle which is kind of odd but when you give it gas under load (neutral it revs just fine) it just trips over itself lack of power, backfires and generally runs like someone pooped in my tank.

I have heard everything from the O2 sensor isnt going to get up to operating temps (its a single wire) because of the headers and i need to replace it with a 3 wire system (check the 3-wire sensor and plug is on the way to wire that in ASAP).

The main issue i worry about is if the ECU is adding a value to the O2 sensors value by default because of the SAI was suppose to be there. If this is the case then even with the 3 wire O2 the system is going to have just as much issues and i need to some how reduce the voltage off the o2 sensor to trick the ECU in order to prevent over leaning the engine.

Now first off i removed the K&N the other day and put in a normal ol restrictive paper filter just in hopes of getting some of the problems fixed, not much of a difference there so back to ground zero.

Other options i found were to get a custom eprom, etc however with the cost of an Eprom i could build some kind of potentiometer controlled voltage reducer to control the volts going to the ECU for about 40.00 rather than 300.00 for a new eprom.

Any insight on this issue would greatly help out guys I am at my wits end.

Maybe call a shop and see if they know what could be wrong with it. Maybe its computer just needs to be re-tuned to the new Headers. :/ Not a truck kinda guy but my Camaro needs a tune up becuase mine was running without anything in the cat and that screwd up my entire tuning! Goodluck

It is an OBD-1 system so its pretty stupid all it looks for is O2 sensor values to give it the correct A/F ratios so if switching the headers out caused the problem due to the SAI having to be removed (IE: Less O2 being force injected into the exhaust manifolds) then the O2 sensor is going to read a richer mixture when in fact it isnt, which in turn gives the signal to the ECU and the ECU leans out the engine. Back to the issue of a 40.00 adjustable pot voltage regulator or a 300.00 eprom "tuneup". The Eprom tune up being the more costly way of forcing the ECU to read a lesser O2 volt value.

I just do not see much of a reason why changing out the headers would cause this massive issue as i have heard so many people in 1988+ K1500s not having to trick O2 or change/tune eproms all because they changed over to headers.

Ok guys just posting an update. I am a complete moron. I went back and started from point one. The truck ran fine until i put on headers and new spark plugs. I double checked my wires and found i crossed cylinders 4 and 8 which was the very reason those two header pipes were not turning that pretty blue color. Fixed that issue and the truck runs better than it did with the manifolds. So problem solved and i hang my head in stupidity.

hahaha
glad you got it worked out.
What brand did you go with?

Sweet man! You're not a moron cuz you diagnosed it yourself and fixed it! Usually its simple crap like that tho.. Great job man! enjoy the new headers

I went with the cheapy flowtech stainless shorty headers that were suppose to be direct OEM replacements to the y-pipe. I can say this. Bullsh*^ the y-pipe was 3 inches shy of bolting up and the flair was to shallow. Luckily there is a muffler shop 4 miles from my house that are the good ol boy type who i have delt with for putting flow master 2 stage muffler on and putting a straight pipe up from the y-pip to the muffler not to mention the pipe work they did for my GSX600F motorcycle so they know me pretty well now. $70.00 and a completely rebuilt y-pipe later it fits those headers nicely now.

Didnt want to go with something to costly on the truck as im not racing it, but i am gearing up for a project with it. Getting it ready to see if this HHO hype actually works. So many yay and nay sayers just figured i would do it myself and run the system with the cheapy stuff so if there is a problem its going to show up on the cheap stuff more than the costly parts quicker. If it doesnt work, no biggy the truck is running better than it ever has when i first bought her before she went to the junk yard anyway.

Thanks but still feel like a retard for not triple checking the plugs the first time around after putting the headers on.

Headers are headers.
The only complaint I've heard about flowtech is that around the part where
All the tubes go into the 1 main pipe (forget what that section is called)
That there can be a little leak there and you can hear TS TS TS TS TS TS
But a quick spot weld can fix that. But what I am gonna do is wrap exhaust wrap around
The headers to help keep the engine bay cooler and help my Cai work better

Good to know. if there is an issue the muffler shop can take care of the welding for super cheap and only takes them an hour.