this is a fresh 355 with tpi. it has modded vortec heads and a zz4 cam. otherwise its pretty stock. the tpi/harness came from a 87 formula 350. its all now in a monte carlo. also has 24# injectors, fuel presssure is set as high as i can get it to go, 40ish. in the last few days the fuel pressure now jumps all over the place. i have a new adjustable regulator im going to put in when i get a new pump and sending unit.

It has a miss in the #5 cylinder and the plug is kins of varnished and smells like oil, but no where near fowling the plug. the motor ****ters and searches for an idle, almost like the tsp voltage is off, but thats cool too.

im hoping to get the fuel pressure figured out first, so then maybe i can find this miss. any ideas would be great thanks. but there is definatly someting going on, it feels like a 6 cylinder.

 

My guess is that you need a lot of computer tuning.

Also, what do you mean when you say the fp jumps all over the place? I'm not too familiar with the tpi regulator, but It is possible to bottom out the regulator on my tbi, which causes the pressure to go crazy, and is definetely not a good thing. I would assume it is possible to do the same with a tpi regulator.
If your fp drops when under load, then you need a high flowing pump. I swapped engines, and was very dissapointed the first time I went to the track. swapped in a walbro 255 and picked up over 5mph in my traps.

As far as the #5 cylinder problem, maybe it is an injector issue? I don't know for sure.

 

thats the pump thats going in it, i get it in about 2 days. looking at the fp gauge it will flutter back and forth from like 30-40 and in the last few days i cant get it over 40. i had it set a 46. i have a prom that has been burned, a guy i know did it just as a general idea. but im trying to figure out the fuel issue before i break out the laptop. and it actualy runs better with the stock prom.

i picked up a new regulator thinking that mine may be bad, for the price i figured why not try it.

next step if the pump doesnt help me out i guess ill pull of the head and have a look.

 

fluctuating fuel pressures point to the fuel pump not delivering enough fuel. Other than that, a lot of tuning is in order.

 

the injectors are svo 24 pound....if it true that gm rates them different than fords? a few pwople have told me that they are more like 28, so when using them have the fuel pressure a bit lower than you would normaly run. is that true?

 

Yes, Ford rates theirs at a different pressure. I belive it's 48psi, but don't hold me to it.

 

Yeah, it definetely sounds like your fuel pump is having a hard time keeping. Just for clearification, my stock pump was doing the same thing, thus causing me to go lean under load. Swapped in the Walbro HP pump, and it cured that problem.

It is worth it to go with the high pressure walbro 255 as well. I don't think there is even a cost difference from the standard Walbro 255. But even if you do not need 90psi (the highest pressure the unit is rated at), it is still a better choice because there is less current draw.

 

The fuel pump is failing...also, you need to adjust your injector constant to 26# injectors to compensate for the richness...set your FP to 45-47psi for best atomization...

Sounds like an ignition issue could be at work as well, especially on the #5 cylinder, maybe a bad wire...

Check for codes, get some datalogging software to check the sensors while running...

These tips should provide you a good start to the process...

HTH,

 

I feel your pain! I have a similar setup with AFR heads and know some people run mid 12's with the same combo. I"m lucky if I run a 13.9! Long story, but it "opened up" and was fast as hell for 4 mo. then i put my charger back on, blew a head gasket, and now it's a dog again? Not sure why? I checked the wide band o2 test which turned out fine! spark is good, checked the cam timing = perfect. I am going to cut my cat's and see if that does anything?? good luck, remember, spark, air, fuel.............

 

wow my car and yours look the samer with similar motors mabey its a curse lol well I m working to get mine running right but same thine i think it\they need chip tuning Ive done everything elkse