Backfire and sluggish performance after 2.5k rpm

[HadesOmega]

I swapped a 82 L28ET into my 76' 280Z. I noticed when I revved it would backfire a lot so I installed my MSD 6A and it revved a lot smoother. I also had it gapped to .040. Took for a spin today and it intake backfires after about 2500 RPM. So far to fix this I have gapped plugs to .030, set base timing back to 15 degrees, and disconnected the TPS. I read from other posts it could be the TPS and I should disconnect it and see if thats the problem, did that and it actually had the same problem but ran a little worse. Previously the engine was running rough during cold start and I cleaned all connectors with with contact cleaner.

 

I also made sure all my injectors were the same. Wierd thing is when I got the engine it came with these teal (sky blue) colored injectors. I heard they were suppose to be brown. But I also heard that you will be fine with NA injectors at stock boost levels. I noticed that when i took the thermostat housing off that there wasn't a thermostat also, maybe they were trying to run the engine cold to compensate for leaner injectors? But I don't htink this is my problem could it?

 

Below 2500 RPM it runs great I can boost fine but after 2500 is where it starts stuttering and backfiring. And suggestions?

[Guest bastaad525]

I've been looking around for a definative list of which color injectors are from which application.

 

I have seen four different colors of injectors on EFI 280z/zx's now, white caps, brown, green, and blue caps.

 

I've been told the white ones are the n/a caps, other than that I haven't heard anything definate. When I bought the donor motor it had 5 brown ones and one green one. Anyone know which are for what?

[slownrusty]

Have you pulled the plugs and checked the color?

 

Try closing down the gap on the plugs and see what happens

 

Also change the head temp sensor right above theoil filter.

 

Yasin

[HadesOmega]

man I did something that made it run smoother O_o, lets see I took the cylinder head temp connector out and put it back in, wiggled the ECU connectors and suddenly my car turned into a rocket ship after 2.5k O_o hmm really annoying how one little thing could cause a large drop in performance.

[Guest bastaad525]

not at all surprising would have suggested it earlier but you had mentioned already cleaning off all the connectors.

 

did you use dielectric grease on them after cleaning them? That will help keep them from corroding.

 

Before I used that grease, I'd have to mess with the plugs every week or two to keep the car running okay. Now I don't have to mess with it.

[HadesOmega]

hmm ok I will use grease sounds like a good idea I used dielectric grease on everything but the ecu connectors. Not too much grease though right? Just a dab over the connectors?

 

My head temp sensor connecter is all busted up though so I better replace that, how often do those sensors fail thinking of replacing it just in case.

 

I drove the car about 100 miles this weekend and its having trouble going up hills. But its a really steep wide freeway hill and I'm trying to take it in 5th which is super tall O_o. It has to use the turbo to maintain speed. My eclipse seems to do a better job getting up it without turbo .

 

The engine doesn't seem as rev happy as the NA one, should it pull strongly up till redline? There really seems to only be power from 2-3k. When I decelerate I get exhuast backfire like pops is that normal, pops more when it deccelerates from higher RPMs.

 

Pulled some plugs too and the tips are lookin white not really white just a small touch of brown on it, like the ceramic part near the elctrode is really clean and the tip is white. Is that normal? I'm thinkin its running a little lean. Maybe I should switch to 7s or put in some of those brown turbo injectors.

[GrayZee]

is it possible that your distributor and/or cam is not installed properly causing your miss firing?

[HadesOmega]

well I've never messed with the cam, but I did adjust the valves could improperly adjusted valves cause decceleration backfire? I'm thinking it could be associated with timing also. The distributor seems to run fine to me. Could it be the timing chain?

[GrayZee]

Yes, if the timing chain is out by a tooth it could cause problems like that. Also the distributor could be out, or even the gear that drives the distributor might not be installed properly. I'm only suggesting this because I helped a guy do a turbo swap this summer. He first got the engine rebuilt at a shop. Well perhaps they know their way around a domestic engine but they kinda messed up this one. I couldn't get it running good, later I figured out that the distributor was WAY out and couldn't be adjusted because the drive spline was WAY out too.. I was surprised it even ran. Not only that.. we found that the camshaft sprocket was out by two teeth. At first we were getting about 110psi on a compression check (on a fresh engine?) My engine with over 120,000 miles has 155psi. After we fixed the timing gear to where it should be, we were getting 160psi. I guess if you want something done right, do it yourself. I just think you should explore these possibilities as they all could cause the problems that you are describing.

[HadesOmega]

hmm well I cleaned the ecu connections with some stuff called kontact restorer, it supposedly cleans and lubricates your connectors and smeared a small amount of dielectric grease on em. Runs really good now still got that poor idle when its cold but when it warm it runs great.

 

I'm thinking the timing is fine then I guess because I get 165 psi per cylinder. looks like she's good to go now just have to figure out where this new driveline clunk is coming from seriously I've never seen a car that has drivetrain mounting problems like this one.