Question: Leaking injectors ? emission values analysis

[keremarsan]

Hi from Turkey , Istanbul ,

I have an 88 with 76.000 original miles. When my car stays more then 5 min and I come back , it difficult to restart the car. When it restarts, there is black fume and fuel smell . There is no problem for cold start or restart hot within 4-5 min.

I ordered fuel pressure gauge and get it from corvette central , I suspect leaking injectors. I also ordered new fuel pressure regulator diaphram.

Here is the numbers : ( New fuel sending unit , inline filter , pump strainer )

- Car not running, key on , after the prime , 43 PSI

- Start the car, car running at idle speed , engine hot , 37-38 PSI

- When accelerating , max 44-45 PSI.

So everything seems to be OK .

But when I stop the engine and the pressure stays at 40 PSI and I lost approx 4 PSI within 10 min ???? when this occures, I don't block the fuel return line.

I don't know if leaking occures with main injectors or cold start injector.

I drive my car for 3 and half years and make 15.000 miles. And most of time, I had this problem that I want to resolve.

Another question is gas emission values :

- CO : 1,7 %
- HC : 170
- CO2 : 12 %
- O2 : 3 %
- lambda : 1,15

the car has no pre-cat , no main cat at all ( the performance and engine response is very good ) but the air injection is operational...

Looking this values, the car is running a litle lean ( no code ) but in fact the performance is very good ( 0-62 mph : 5,6 sec , 0-80 mph : 9,3 sec ).

If the injector leaks , i think the car must run a little reach instead of lean ? or the air injection is adding air in the exaust but there is no cat so the values are not real ?

I think to purchase new ACCEL injectors ( stock , 24 lb/hour)
Any information will be welcome thank you

kerem

 

[Hib Halverson]

I agree with your diagnosis of leaking injectors.

If you're going to replace them and the engine is not modified, use a stock injector or an aftermarket unit that flows the stock rate.

 

[surfer93]

Put a OHM's meter on the the injector's when car is hot, if an injectors is below 13 or above 17 OHM's replace.
Check the vacuum hose on the fuel pressure regulator for gas, if so, then it is bad.
Also, if you lose fuel pressure fast after shut down, you have either a bad FPR, bad injector, leaking pulsator or bad check valve in the fuel pump.

 

[ex-x-fire]

Going from 40psi to 36psi in 10 minutes is normal, a leaking inj. will quickly drop your press. to zero. Try cleaning your maf.

 

[keremarsan]

Thank you very much Hib

Sometimes ago , you have already say me that my injectors are leaking , it is time to replace them now

I think the stock rate is : 24 LB / Hr ,

MR ex-x-fire says that the decrease of 4 PSI within 10 min is normal ? you don't agree with this opinion ?

The pressure must stay at the same value during how many time to be able to say there is no problem on injectors ?

 

[keremarsan]

Thank you Surfer93 ,

I already check the vacuum house , there is no sign of gas in the hose , so it is OK I Think , but if I change the injectors, I will also put a new diaph on it because it will be not an easy job to remove all the plenum etc .. I don't know if I will do it by myself

 

[keremarsan]

Thank you Ex-x-fire,

I will try to find also something to clean the MAF , there is not enough staff special in Turkey and no way to order it (

( I change more then needed the air filter , but I have a new MAF Burn - off relay that I think to change it also )