Driveability problem

[Ninja GSX]

I have a 95 GSX. The problem I am having is when I accelerate. If I give it too much throttle too soon it starts to miss. The miss can go from occasional to evenly spaced, rapid fire. Last year replacing the plug wires and plugs seemed to fix it for a while. Then at that time I had an oil leak that got some oil on the pug wires and one of them swelled up. I replaced it and that seemed to improve it a little bit but is still does it.

Then today I had a check engine light. The fault code was P0202 injector circuit #2 cylinder. I cleared the code and it hasn't come back but I am wondering if I have a bad injector, throttle position sensor or something else.

So I am looking for some suggestions as to how to trouble shoot this. Thanks.

 

[g4ebguy90]

Odds are you got a bad injector . Damaged harness, or bad ground for the injector, which I assume is the ECU.

 

[Ninja GSX]

Thanks for the reply. Driving around today I noticed that it occurs when boost gets around 10 psi and it was worse today than yesterday when it was a little cooler. I made a quick visual inspection of the wiring it looks okay. I thinking it may be the injector. If I pull it out to make a visual inspection are there any signs that I could look for or am I going to have to test it and how do I test it?

edit: Something I forgot to add is I got the impression from the second owner that the first owner let the car sit in his backyard for a while before he sold it to him. He had to replace the fuel pump which sounds like the fuel turned to varnish on him and gummed it up.

 

[KYAWD]

I had that problem and it was the injector plug was loose do you still have the clips on it?

 

[34tftf]

also their are three seals on the top of a walbro fuel pump that if you install them wrong your fuel will cut out. but idk if that would be the problem for the dtc you had but it would be something worth looking into

 

[KYAWD]

Yea mine started due to me hiding my throttle cable under my IM

 

[Ninja GSX]

I will have to look again at the clips to make sure, but I think they were still there. The car runs fine when I'm not giving it a lot of gas and getting into boost. Obviously I could be wrong but, I would think that if the wiring or a connection was bad it would run bad all the time. When it hits the rapid fire missing, it feels like it is occurring with the frequency of a fuel injector cycling. But if I back off the gas it smooths right out.

Thanks for the reply's guys.

 

[superpenguin]

I would pull the fuel rail loose and have someone crank the car over while you watch the pulse from each one. Also make sure while there off you check and make sure the black ends of the injectors are in tacked. Because if they are broken you injectors are junk because they will not give you a good spray pattern.

 

[Ninja GSX]

Okay. thanks. Driving it today I certain it is only acting up when I build boost. Otherwise I can go through the whole RPM range with no problem as long as I don't give it too much throttle and go over 6 pounds of boost.

 

[spooling hard]

Add more fuel if you have Link and the injector/pump power to do so. Also, like the other guys said check the injectors.

 

[Ninja GSX]

Thanks for the input. I didn't have time to check the injectors today before I went to work and it has been raining. So I still need to do that. On the way to work the problem got way worse and the check engine light came on. I got the code and this time it is P0301 cylinder 1 misfire.

Now it has no power but if I get it up to about 3500 it will start to run smooth. I am waiting for it to cool right now so I can pull the spark plugs and check how the engine is running. I'm also going to try swapping out some of the plug wires. Something I guess I should add is on Friday I replaced the stock exhaust with a 3" DP and cat back that eliminated the catalyst.

 

[spooling hard]

did you check the wire resistance? it should be 4k/ft of wire. dont be a parts replacer, be a mechanic! and the exhaust shouldn't make a huge difference. I say check the injectors first

 

[Ninja GSX]

did you check the wire resistance? it should be 4k/ft of wire. dont be a parts replacer, be a mechanic! and the exhaust shouldn't make a huge difference. I say check the injectors first

I feel you on being a mechanic, not a parts replacer. I got lucky and found the solution by chance. I was on the VFAQ looking for the cylinder order and I saw this article. It seems this is a design flaw with our cars.

Magnecor Race Wires: Mitsubishi twin cam technical bulletin

When I went out and looked at the #1 plug wire it had a little light grey spot on the end just like in the picture with the article. I swapped that wire for one I got from U-pullit and now it's pulling better than ever. I cleared the fault code to see if I get a new one.

Thanks for all the help guys. Now I can enjoy my new exhaust.

 

[spooling hard]

Good find! Im sure that will help a lot of people down the road