I know injectors are discussed here almost daily. I have come to the decision that I need new injectors because my 89 is running as rich as they come.

Some background...I bought my car sight unseen and the engine has been monkeyed with quite a bit. I think I have a higher lift cam because it sounds like a funny car dragster. I have determined through a fuel pressure test that I loose pressure quickly like 5 minutes after I shut off the car. I also verified that the regulator is good by clamping off the hose during the test. My spark plugs reak of fuel and the exhaust reaks of burning fuel when I fire it off. Plus, once the engine gets hot the car is really tough to turn over....hence, fuel injector problems.

I am not sure what pound injectors I have. I plan to find this out soon by getting the model number off the injector and a little help from a corvette forum dude.

My question is...if I have 24s or 30s, how do I figure out if my chip has been mokeyed with and if I go with stock 22s will my car run like crap if the chip is set up for something other than stock?

Thoughts?

 

run datamaster and get the readout, that will give you some info first. Pull the ECM and you'll be able to tell if you have an aftermarket chip or not, aftermarket will be on a piggyback adapter, stock will not, you can't mod the stock chip. If its aftermarket junk, go back to stock chip 1st.
you can prob go with stock injectors and do a AFPR to help tune the fuel pressure, replace all o-rings with injectors. Do your testing and research first before throwing thing at it.

 

It isn't entirely true that you need a "piggy back adapter" for an aftermarket chip. Some, such as TPIS use a stock GM chip and cover on tunes /re-burns.
There is only one real way I know of to tell what has been done to the chip. That chip would need to be uploaded (opened) through an emulator to a laptop/PC, and then compared to a stock bin file (chip) of the same year. If the inj. constant in the chip has been changed to accommodate a bigger inj., swapping to a smaller one would not be a good idea (this is of course providing the tune was good to begin with) as this could cause an extreme lean condition. Again this would depend on the state of things, and if the chip has even been changed to accommodate a bigger inj.

I would first determine if they are leaking, and what size inj. is actually in the car. Most inj. can be looked at visually to determine brand and size. This will help in knowing if mods in this area have even taken place. If the inj. have been swapped out to a bigger size, you could then upload the info from the chip and make sure that the two correspond (inj. lbs.rating and inj. constant in the chip), then do a compare to a stock bin file (tune) to see exactly what has been changed.

As to the "fuel dragster" sound, that could be a few reasons. Maybe it has been modded, or the tune or condition (mechanically) is just rough. A rich condition can be accounted for in a variety of ways, inj. 02sensor etc.etc. Pressure drops can be inj. but other tests are needed. What you will need to do is go through all the normal test procedures (an FSM will help here) to assure what is the problem/s and that everything else is mechanically sound.

 

if you can read the part number on it i can tell you exactly what it is . Also is it a multec? If it is there were no 30's. only 19 22 24.

 

The Injectors are solid black in color. The number on the side of the Injector is D18108A.

 

they are 24lb lucas

 

Besides cam and (slounds like) injectors what other mods can you detect to the engine??

Does it have an adjustable fure pressure regulator (AFPR)?
What fuel pressure do you read at idle, with the FPR vac line disconnected and plugged?

 

I do not have an adjustable fuel regulator.

I read about 40 lbs at idle of fuel pressure.

The FPR vac line is not disconnected or unplugged.

Okay, not really what I wanted to hear. 24 pounders not being stock makes me think someone wanted more fuel for a reason.

What would you do? (1) Replace with stock regardless of a possible cam (2) Replace with 24s hoping that the chip has been modified for them or (3) Pull the chip and somehow figure out what it is configured for and replace the injectors with whatever the chip calls for.

BTW - Thanks to FICINJECTORS for the info.

 

With a few bolt ons I just installed a set of Accel 23lb/hr injectors to replace my OEM 22lb/hr units and the ECM is still maintaining stoch A/F in closed loop. Though it does sound as though you may have some leaky injectors.

I don't think your cammed engine should have a problem with 24lb/hr injectors if it has a stock chip. You could drop the ECM and take a look at the CalPac to see if the EPROM has been modified.

You should try to find out what are all the mods to the engine before trying to fix a rich run problem.

Pull any trouble codes to see if there are any other issues.
Is the exhaust stock, does it have FL headers??
Has the air filter housing been modified?
Has the MAF and/or plenum been modified?

BTW, other problems could make it run like it was "cammed"; I think a faulty MAF or MAF relays can cause very rough running.
Also some faulty sensor(s) can cause the ECM to enter "limp home" mode where the timing is advanced and the A/F is enriched to protect the engine.

 

I have pulled the codes, none to be found.

Stock exhaust. Not really. I cut out the precats. It was running like a dragster before that and doing that changed nothing. It has flowmaster mufflers.

When I got it, the air filter housing was stock as pie and it sounded like a dragster. I have since cut out the lid for more air flow. Still sounds like a dragster.

As far as the plenum, I have larger runners.

No matter what I do to this car it still sounds like a dragster!

I really don't mind the dragster sound, but when it runs like I am running 80 octane gas that is too much.

I even got pulled over by a cop the first day I had it and SHE (the cop) said, "DAUM Son, this car smells rough - you might need to take her to the shop."

 

Killebrew says fuel pressure should be tested at idle w/ vacuum, idle w/ vacuum dis-connected, and WOT (long hose w/guage taped to windshield).

 

And the results should be?

RK

 

Do you have a laptop computer ? If so go to Moates.net and get a cable and a copy of Tunerpro RT. Or get Datamaster from TTS Powersystems. This will let you scan the car and see all the sensor readings to find out what the motor is doing and get a clue what it needs. Tunerpro is free, Datamaster is around $125. I think its wort it. At any rate a scan tool can be very educational and a great tool.

 

Check your gas cap for losing fule pressure after shutoff. A gas cap seal can get hard and go bad and not seal correctly. A $10 item that may help with the fuel pressure bleed off problem and if you have to get emissions testing will be required too!