Intake Backfire?

[Mike3889]

Hey I'm not a noob but I really can't figure this one out and I don't really feel like bringing it in when I'm sure I can get an answer on here and fix it myself. I have a 1992 Plymouth Laser RS AWD. My problem is when my car reaches 5500-6500 rpms it will just like cut out which seems like a backfire. The backfire is NOT an exhaust backfire. So I think that it may be a intake backfire, what would cause this? It also does not do it when in neutral. Everything has pretty much been set back to stock to try to figure out the problem easier. If anyone has any idea of something other than timing because I did check that so I'm somewhat sure it's not that. Another clue that may help is it has been doing it ever since I changed the head. Vacuum lines? Sensors?

 

[silver bullit]

You're not sure, so check timing again right this time.

Do a boost leak test, You do anything to it recently?

 

[Mike3889]

No the only thing that I did was change the head. It ran fine before I did that.

 

[silver bullit]

No the only thing that I did was change the head. It ran fine before I did that.

Still have to take the head off...

Did you make sure the crank, cam gears and balance shafts (both) are lined up... you just said you where not sure after checking them.

Its not hard to check them correctly.

 

[Mike3889]

I lined up all the timing marks when I put the new head on. I also put a new timing belt on when I did this. I have done timing quite a bit. I already replaced the engine before.

 

[Defiant]

Re-check the timing. How old are the plugs and wires, and are the plugs NGK BPR6ES at .028" ?

 

[steve]

I was just wondering does it really have any effect whether or not the injector clips are on? I feel dumb asking but you mentioned that they should be on? I don't have any on but my car runs fine just has a fuel cut at 5500-6500 rpms that I was wondering why it is doing that and I can't figure it out.

Does it make any difference? Yes, it can make a lot of difference. People have problems all the time with intermittent connection to the injectors from missing the lock clips.

I'm not sure that would be the cause of your problem here but it's easy to test. Put some clips on or some other form of securing the connector to the injector.

 

[Mike3889]

So nobody has any idea? I did the boost leak test and found a couple small ones but that didn't fix it. I bought new plugs NGK BPR6ES at .028. Could it be injectors? I tried to check them by testing for ohms not sure if that is how to test them or not? Any ideas on what could be giving me a fuel cut?

 

[viprez586]

Does this backfire have an abrupt halt in acceleration? Occur only at WOT?

Do you have an aftermarket boost gauge? How much boost are you running?

Sounds to me like fuel cut if you get this abrupt halt. Get a boost gauge the one on the dash is inaccurate.

 

[Defiant]

So nobody has any idea?

Well, THIS was an idea:
Re-check the timing. How old are the plugs and wires, and are the plugs NGK BPR6ES at .028" ?

I did the boost leak test and found a couple small ones but that didn't fix it. I bought new plugs NGK BPR6ES at .028. Could it be injectors? I tried to check them by testing for ohms not sure if that is how to test them or not? Any ideas on what could be giving me a fuel cut?

Is it fuel cut, or an ignition cutout?
How old are your ignition wires?

 

[Mike3889]

Not really sure, but I'm not sure why that would matter when the car ran fine before I had changed the head. So immediately after changing it it started to give the fuel cut. Maybe the Coil pack if anything?

I already have an aftermarket boost gauge. What sign would appear on the boost gauge if this is a fuel cut?

I mean I guess there really isn't anyone on here that can tell me anything other than what I know or have tried but I thank everyone for trying.