Hi Flow Injectors

[jnsampson]

OK, here we go again. I recently had to have the injectors replaced on my 85 C4 L98. The long story of this is that in 1985, Chevy, in its infinite wisdom had two (2) different versions of injectors in the L98 of that year. One set was manufactured by BOSCH, the other was manufactured by another company (can't for the life of me remember the name. Needless to say, they aren't interchangeable.

Rather than spend $165.00 PER INJECTOR from Chevy/GM, I bought 8 injectors from Ecklers. These were advertised as "performance" injectors for mildly modified engines. The flow rate for these injectors is 24 lbs. / hour. The stock injectors I used to have were rated at 19 lbs. / hour. I HAD to replace the injectors for 5 of them were leaking.

Now, the car runs a bit erratic at 1500 RPM / 35 mph in Drive (w/o Overdrive). It's like a bit of a surge. At highway speeds, it's fine. Acceleration is fine too (ran it up to 102 w/o problem)

Chevy is now saying my O2 sensor is trashed due to the increased flow rate of the injectors and that the computer cannot compensate for the higher flow rate.

I'm not buying this one for a minute since Ecklers and others have said that the injectors should work w/o problem. Furthermore, if the O2 sensor has gone haywire, the engine, unless I'm missing something, would simply not run properly at all.

Am I missing something here? Any ideas?

Thanks,

John Sampson

[cntrhub]

Are you using a stock air cleaner? Change to one that lets more air in. The fuel/air ratio my be just a touch off at the bottom, and that's all that is needed. It may need a little more air to compensate at lower rpm is my guess? Better wait for a "driveability tech" here on CAC to help you with this one.
I agree with you about the 02 sensor. How could the sensor be "trashed" if the car runs good at sustained highway speeds, and throttle acceleration?
I would logically guess that if the 02 was trashed, it would give a wrong signal, and run like junk at any speed...plus, spit a code!
I assume you changed all 8 and not just the bad 5 injectors?

[Vettelt193]

did you try lowering your fuel pressure? also, did you reset the computer (disconnect the battery) when you swapped the injectors?

[Edmond]

If you weren't getting enough air in, the computer would compensate for that by lowering the fuel right? Isn't it something like a 14.7:1 air/fuel ratio, by weight?

[Vettelt193]

our cars compensate with shorter pulse, they can't change the fuel pressure... so if it is getting too much fuel, it will shorten the pulse, which could cause a bad spray, causing bad ignition, causing a bad running engine....

realize that going from #19 injectors to #24 is a big leap... almost 25% higher.... a drop in fuel pressure will compensate for the bigger injectors while keeping a decent spray pattern

[WhalePirot]

But the O2 sensor could have loaded up, as well, from the rich fuel condition. Their life is only 25k or so, though I have gotten more.

Try a lower fuel pressure as one of the easier remedies and reset your ECM. Get this ironed out before you load up your CAT as well.

Ensure your ignition system is okay, as well. I fixed an overdrive cycling problem once by changing plug wires! Must have been misfiring, telling the ECM to go back to closed loop.