Hey guys, I just picked up a manual 6 speed 1989 that the previous owner had installed a Procharger and I was looking to get some input from you others running a similar setup on the l98, the car has the following work and do note that this was built in California with the intention of it being a CARB legal build but I have a work around so If modifications need to be made for the car to run better that is okay with me.

-Freshly rebuilt block and heads done with a little over 1500 miles on them
-Complete Procharger intercooled setup with about 200 miles on it
-Procharger Pro pump and FMU unit
-Brand new Injectors (I believe stock)
-New Plugs, wires, cap and rotor ( I believe they are the correct ones as the previous owner went to a couple different shops getting this figured out)
-Brand new Catalytic converters
-New MAF sensor
-New 02 sensors

The car has been gone through entirely and has plenty of new parts on it but I don't see any of those being related to this problem I'm having.

I drove the car about 60 miles home without any issues, Oil pressure was perfect, Temps didn't get over 200, no hesitation on acceleration and when I got home there were no leaks or any signs of any issues.

Although the car basically hesitates when it gets to about 3500 RPMS and will not go any higher and then the temps jump up to 220-230ish and do not go any higher. I am going to install a fuel pressure gauge and boost gauge asap but for now I would like to see if anyone else has had a similar issue.

Next steps for me are going to be pulling plugs to inspect for any sighs of lean conditions, I am going to test the fuel pressure and do smoke test for any boost leaks but nay feedback would be greatly appreciated, this is my 3rd C4 but my first supercharged car so I apologize for my lack of knowledge of this subject.

 

Hi

Supercharged Corvette is the best, I like it a lot.
What model do you have?
Do you have a picture of the engine?
I have a P600B and it's really loud but I like it.

I recommend installing a wideband gauge if possible. It has saved me many times.
Is it possible for you to take data logging?
It sounds strange if the revs don't rise above 3500rpm

 

I've always wanted a supercharged corvette and I'm already very happy with it.
I have a P600B as well and I absolutely love how loud it is.

I believe the car does have a wideband already installed but in all honesty I am unsure of what to watch out for in the sensor, are their any reading that are red flags that I should know of?

I have only data logged on OBD2 cars so I do need to get all necessary hardware to do so but I currently can not.

 

A weak ignition system will miss at higher cylinder pressure.
I have an MSD 6AL and I can't run standard gap at higher boost with that.
Will it rev higher at part throttle?

 

I actually have not tested this at partial throttle, I will give it a shot when I get home.

If you don't mind me asking what spark plugs are you running?

 

Be careful with the timing. Do not run full timing with boost. Has the ecm been tuned for the larger injectors and/or timing retard? Is there a boost retard module? Assume that everything done and recommended by procharger is wrong.

 

Where are you located?

 

Hopefully it hasn't lifted the top off a piston.....I would do a compression check first. After that if OK, if you're in SoCal I can help you out.

 

I'm located in the Costa Mesa/ Santa ana area.

I had done a compression test to which there were no issues, would you happen to know of any tuners in socal?

 

The car is currently on the stock ecm and injectors. I am starting to see more people stating the same that prochargers recommendations are incorrect.

I am currently looking for a tuner in my area who can get the ECM tuned and to get the timing adjusted correctly.

Is a boost retard module a must or will a tune suffice for the timing requirements?

 

I'm glad to hear the compression is good! If you are willing to learn and diy Id be more than happy to help. If you are more of want to drop it off and get it fixed I'll just advise. I'm about an hour and half away from you (depending on traffic!) An MSD BTM would handle safe timing retard and increasing spark, then would need to tighten up spark plug gap and check the plug heat range. You can't tune boost spark retard in the stock program. With larger injectors if the injector constant wasn't changed in the prom then you are running real rich all the time. Also needed is a fuel pressure gauge to "tune it" with the FMU.

 

I really appreciate that, with the ECM tuning I prefer to let someone who is experienced handle it, (especially with Moates going out of business). I will be picking up a fuel pressure gauge asap as I can see every reason It is needed.

I looked briefly into the MSD BTM, I like the fact that it is CARB approved. is this a unit that you have used?

 

Yes, running it now. You really need to determine what injectors are in it, try to get a look at a part number.

 

I have cooler plugs, Accel 0414S which are also shorter.

 

Update: After calling just about every shop nearby I found one who is able to tune the car for me, We discussed that the current injectors (24LBs I believe) will suffice with the amount of boost I am running although I will be buying and installing an MSD Boost control module as well as making sure the plugs are the correct temperature stage.

I appreciate all the input you have all given me greatly and on that same not if there are any recommendations for Fuel pressure and boost gauges please advise on which ones have done well for you. The only brand I have looked into is Glowshift and It looks solid but I am unsure if this has proven to be well for others

 

I have the glowshift dual vac/boost and fuel pressure gauge and it works fine. Another couple things to figure out-on the rebuilt engine does it have forged pistons, compression ratio and were the rings file fit/what ring end gap.

 

I am glad you found a shop to tune this. The Pro Charger way of using a FMU and stock tune and injectors is a poor way to try and make the car operate.

-Too much timing
-Too much fuel pressure probably causes the injectors to lock up as fuel pressure spikes to over 80 PSI
-Need to close up spark plug gap to .025 to fire the plugs with high cylinder pressure.

Need the correct size injectors and tune to make this combination work.

 

With some know-how, one can extend the range of the maf and load signals in order to control fueling and spark for increased load (boosted) operation with appropriately sized injectors. With the stock maf, you have about 50% additional range to work with. Beyond that there are some other options. You are free to search for my old posts involving Blowerworks products.

Here's an example log from one of my (Blowerworks) tunes for Paul's 86 Procharger car: https://datazap.me/u/tequilaboy/160-...77-163-279-205

He lives in Torrance CA.

You can use load as an indicator of boost. With load of 255 the manifold pressure should be near atmospheric pressure. Load > 255 is boost. This car probably makes 8-10 psi of boost. The maf air temperature is another good indicator of boost activity (blow-through maf with integrated IAT located after the intercooler). This car has a CX racing (ebay) front mount intercooler, not the Procharger intercooler setup and my old Lucas 42 lb/hr injectors with increased fuel pressure (maybe 55 psi). No FMU. No BTM.

Here's another log with better fuel control (same car): https://datazap.me/u/tequilaboy/6013...5669-5757-5705

 

Thank you for this insight, I am going to get some new plugs thrown in this weekend with the correct gap and see if that helps much.

I also noticed that the air filter is atrociously dirty yesterday and I am going to clean it out and see if this helps anything although I doubt it will.

 

I really appreciate the data/ I will be searching through your old posts for references