Misfire intermittently Q45 94 126k

[jhudson]

Engine runs like top but very intermittently acts like it's running on 5-7 cyl. Unless rev'd will die, but can immediately restart. Rev 2k for a few seconds and it will be OK for a while, eventually runs fine for a few more days. CEL comes on sometimes when this happens, but just recently. Have run tank almost dry and added 5-6 gal about 5 times thinking if it was bad gas it would be flushed. Any tho'ts?

[maxnix]

Try ISO-HEET? How does fuel pump sound? Fuel filter? BG44K periodically?

If you can give us any maintenance history, it will help.

Welcome to our club!

[Q45tech]

Members should pay attention to questioners location Dallas, where ethanol has been in use since May-June 2006.

A beautiful test is to change the fuel filter, then drain the old one on white paper towels and use shop air to blow out [reverse flush] the residue........it will make you faint thinking about what didn't get filtered.

All that funky black stuff is the inside of hoses [starting at the tank farm ending up in your car] that are being eaten alive.

[jhudson]

thanks for prompt replies. I'll try to answer both in one reponse.

History: had new plugs (part of 'tuneup' at 100k). At 110k had valve cover gaskets replaced due to oil leak on passenger side of engine (right side?) requiring removal of intake manifold and all associated attachments. Mileage was always worse (slightly) and still idles 900 to 1000rpm out of gear (800 in gear). Have not used any fueld additives so will give your HEET suggestion a try.

As for filter, filter and pump replaced around 90K (near as I can remember). Where's the filter and I'll try cleaning it (or replace it if I can get by parts store first).

Again thanks.

[maxnix]

1.) Have not used any fueld additives so will give your HEET suggestion a try.

2.) As for filter, filter and pump replaced around 90K (near as I can remember). Where's the filter and I'll try cleaning it (or replace it if I can get by parts store first).

1.) ISO-HEET only! Never HEET (methanol!)!

2.) Only use OEM fuel filter on passenger side of engine. Read posts on relieving fuel line pressure. http://www.infinitipartsusa.com

[Romeo5k]

Engine runs like top but very intermittently acts like it's running on 5-7 cyl.

Have you checked your spark plug coils, and also maybe injectors? Those are a priority to go out ever since ethanol came to us. The hardest part is just finding exactly which one has went out.