Prom tune in the Northeast

[ZR-1 Mack]

Originally Posted by 91MinuteMan

When I got my Z last fall I put in a Haibek chip. I would hate to think that I have to drive to go to Haibek's shop from Boston to fine tune the chip. The Vette Drs told me that they don't do prom programming. Any suggestons?

Out of curiosity is there a problem or are you just adding some custom features on the chip you have? The reason I asked is adding the custom feature is only $100 while the dyno tune is $200/ hr. (1/2 consultation and 1/2 facility charge) plus the travel expense.

[91MinuteMan]

Originally Posted by ZR-1 Mack

Out of curiosity is there a problem or are you just adding some custom features on the chip you have? The reason I asked is adding the custom feature is only $100 while the dyno tune is $200/ hr. (1/2 consultation and 1/2 facility charge) plus the travel expense.

No major modifications in the works--it is just that beneath the sound of the exhaust and tire road noise I am almost sure I hear steady knocking on acceleration, but honestly I wouldn't bet my life on it. I am going to pull the plugs this weekend and replace them with one step cooler plugs and see if this helps. I also am not happy with the idle as it occasionally, randomly and infrequently has started to fluctuate. The car also tends to crank 3 or 4 times before it starts, warm or cold, although sometimes it starts quicker. Overall the runs pretty good and I always have to consider that I may be too critical.

[FU]

Knocking or pinging ?
One range colder than stock is good for a car that is stock or some top end mods.
Red Line injector cleaner may help out a bit.

[91MinuteMan]

Originally Posted by FU2

Knocking or pinging ?
One range colder than stock is good for a car that is stock or some top end mods.
Red Line injector cleaner may help out a bit.

I would say ping is a better description. The engine is mostly stock with a K&N filter and port matched intake plenum and exhaust. I will try the red line.

[ZR-1 Mack]

Nothing wrong with getting the most out of your car. I was thinking about a Haibeck chip but I don't think I want to do it until after I change out my existing OEM injectors first $$$$. I replaced a bad primary injector last May and the next time one goes I'm doing all 16.

[91MinuteMan]

Originally Posted by FU2

Knocking or pinging ?
One range colder than stock is good for a car that is stock or some top end mods.
Red Line injector cleaner may help out a bit.

Well, the colder plugs are in and I've done a few high rev blasts down the Mass Pike with the red line in and it sounds a lot better. New question, I have a habit of drifting to a stop clutch in with gears in neutral (dating myself, I learned on a 3 on the tree and this is how my dad taught me to drive, so it is now well engrained). From the time I put in the clutch until I come to a stop the revs run at about 1200. When I come to a full stop they go down to about 700, which is the normal warm idle speed. The Z is my first manual with a computer controlling the engine so any thoughts whether this is typical?

[tomtom72]

I think that the idle speed "hang" in neutral @ coast down is a program that reduces exhaust emissions upon de-accleration. Back in the old days, around the early 70's, some cars had de-accel valves. I know my 72 V6 Capri had one. It did the same thing that my 90 Z does when you coast down from speed in neutral to a stop, I'm that old too!

It seems that the program will not let the motor return to idle speed instantly but rather the idle speed seems to come down in two steps & takes a few seconds to get back to 6-700 rpms as I coast down to a stop in neutral in my Z. I even notice that if I coast down to a stop in gear it seems like I loose my compression breaking for brief periods & then it's there & then it's not & then it's there again. I figured that since my ECM was not setting any codes that this must be part of the emissions program?? I don't know enough about EEC motors to say for sure but mine does this all the time and it's passed emissions testing two yrs on a dyno here in NYS so I just figured that it is "normal". I would think it prevents a rich condition during closed throtle de-accleration??? I know that's what the idea of the "de-accel" valve was in my Capri, rich emissions prevention @ de-accleration.

[91MinuteMan]

Sounds like a reasonable explanation to me. Knowing that this happens to at least 1 other Z takes it off my mental check list. Thanks.

[haber rj]

Hello gentlemen yes it has been awhile since I have been on the form, I finally got situated in the new position at work and boy I thought I had problems with the car. Well I managed to find the time to install the new RC injectors and a set of the plenum power plates and the car runs fine. It was so nice to fire it up again. We made a few dyno pulls on Monday and the new prom works great up to 6900 R.P.M. making 370 H.P. to the ground but then the air/fuel reading went from 13.5 down to 11.5 from there to 7200. The horse power reading didn't fall off, so I have to send the prom back to Aaron at S.G. Corvettes for some final tuning. This is a bit of a pain not having a tuner that can do all this stuff with in a reasonable driving distance. Oh well we will play the FedEx game back and forth for a few times again until we get it right.
Haber rj

[tomtom72]

Haber rj, those are some nice numbers! Glad to hear your Z is back to it's old self. RC sells some nice parts. Also glad to hear that the job is a good fit.


Tom