L98 running rich

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May 18, 2022 | 12:44 AM

Primos

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4th Gear

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L98 running rich

I have a 88 l98 in my 86 TA and she is running rich. I have been through the thing over and over. Changed many parts that i thought could be causing it and still rich to where i have some smoke and raw gas smell out the exhaust. Any ideas or help greatly appreciated.

May 18, 2022 | 01:13 AM

Primos

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TPS, plugs, wires, distributer cap and rotor, ICM, CTS, all new. Have a code 45 (rich condition) so im guessing 02 sensor is good. Have checked the injectors all seem to be working correctly. Only thing havnt replaced is mass air flow sensor but dosnt seem that old.

May 18, 2022 | 07:04 AM

ex-x-fire

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Check the fuel pressure and bleed down rate.

May 18, 2022 | 10:47 PM

65Z01

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From: SE NY

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Indeed, if FP is too high it will cause rich running.

Pull, say, #1 spark plug to see if it shows rich running, just for verification.

May 19, 2022 | 01:02 AM

GREGGPENN

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From: Overland Park Kansas

2020 Corvette of the Year Finalist (appearance mods)

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Are the injectors new? If so, are they the right size? If not, know L98's only monitor DS exhaust. If 1-2 injector(s) are malfunctioning, the ECM will fatten up the fuel -- even if the other 6-7 injectors are performing correctly. Check injector Ohms to make sure they are all the same (16 Ohms IIRC)

You could also have a "stuck" injector

May 19, 2022 | 01:08 AM

Primos

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Injectors arnt new and havnt checked the ohms only did the old broom stick trick and they all seem to be ticking the same. Will check ohms tomorrow. Thank you guys

May 19, 2022 | 02:35 AM

stew86MCSS396

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From: Liliha Bakery stuffing my face with coco puffs!

Quote:

Originally Posted by ex-x-fire

Check the fuel pressure and bleed down rate.

Disconnect the vacuum hose to the fuel pressure regulator and make sure there is no fuel in the hose. If the diaphragm in the fpr is leaking, unregulated fuel can be introduced into the plenum near the 6 and 8 intake runner. Pulling 6 or 8 spark plug may indicate rich running condition in this case. By design, I don't foresee a fpr failing in which normal operating fuel pressures will be exceeded causing a rich condition.