I’ve been chasing this problem for almost a year now finally decided to put it on here. When I’m cruising and shift to the next gear the car seems to sputter/hang in the rpm until I gas out of it. Doesnt do this at high rpm runs fine after that. It got really bad last weekend when I drove it in the rain which keeps making me think it’s electrical. I thought it was the fuel pump at first here’s a list of things I’ve already done.
1.new fuel pump and fuel pressure regulator.
2. Checked all grounds on the engine and connectors.
3. Swapped coil packs from a friends car.
4. New spark plugs.
5. This concerns me it will drop 10-15 psi fuel pressure in 20-30 minutes should it be like this or hold pressure for a long time?
6.checked all the fuel lines for leaks can’t find anything.
7. Put new fuel pump straw with the new pump
8. pulled injectors out and cleaned them the best I could. I’m sure I’m forgetting to list things I did. Not sure if it shows my mods in my signature haven’t been on here in forever.

 

The hanging RPM is screaming vacuum leak to me. Can you do a log while driving and look at fueling trims? I know I told you previously but I still miss my Tri-Z….

 

I will definitely look at that today. I looked for vacuum leaks the old school way a while back. I’d say pick up another Tri z but they’re freaking expensive now. I ride mine almost everyday. I’ll try and post a picture of it later today.

 

Of course the stupid car runs perfect today. I recorded the data I have no idea how to read it. Let me see if I can post the video.
Go figure the video is too big even on the smallest setting I can only put one

picture

 

I’m going to take someone with me and record the data in a real quick video so I can post it.
heres the tri z

 

Are the long terms turned off? That's lame

 

I guess so they didn’t come off zero the whole drive. I’m assuming those are supposed to be off since it’s a hci car and no cats.

 

16% difference in short term side to side is pretty big.

What did the old plugs look like? Im guessing a leaky injector on the passenger side and one plug will be more black.

 

The better the tune the better it's going to drive and act year round, if it's just running on the short trims and it's that far off it's going to be far from smooth. A lot of tuners turn off the long terms and I just don't think that's the right answer, I think the right answer is a correct ve table for the application. It's a long-terms aren't turned on then the tune isn't complete Imo I daily drive 14° overlap and zero drivability issues. It just takes a nit pic to put the right numbers in the tables

 

I guess I’ll have to hit up my tuner here in az. It’s nic d tuned he’s pretty well known. Only issue I always have with him is he bitches about my 98 pcm every time I’ve seen him. It’s kinda annoying.

 

I’ll pull the plugs and get back to you with pictures.

 

both rear plugs are running lean.

 

I'd be a bit concerned about that oil on the plugs.

 

it’s anti seize

 

Do not put anti seize on NGK plugs. That’s per NGK data. Anti seize will actually hurt performance fwiw. The plugs need as good a ground as possible. Anti-seize hurts the ground path. We did a lot of testing on this 30+ years ago.

 

good to know I’ll clean it off

 

I would be so bold as to say the opposite. The back 2 look normal, the rest look like a dirty/weak spark.

 

I agree here with Kubs. Unless this is a boosted build, your rear plugs look good, and the front 6 are reading very rich.

 

It does run rich where I’m at. Car is tuned for Phoenix which is about 1000ft elevation. I’m northern Arizona at 5000ft elevation. Should I start with a fresh set of plugs and re check them?

 

Ok I guess my plugs are just junk I moved the two that looked ok to the front and drove it for a while then pulled them back out they still look good.