cch

Got engine running this morning; reset ecu, 14* timing, fuel pressure set at 42 lbs., steady and smooth idle at 1000rpms. Went for a 2 km drive and it was spark knocking... notched it down to 12* and went for a ride and spark knock stopped except faintly in 5th going about 90 kms. Drove lightly for about 25-30 kms...Figured we'd try a 1/4 mile pass (marked off on back road), did it, went great... 5 seconds later the car started clanking and loudly knocking... it bogged and shut down. Confused, started the car a minute later, it struggled and knocked so I immediately shut it down and got a tow back. Checked valve train and all was fine. Pulled the passenger head and found the head gasket slightly burnt between the 2-3 cylinder wall. Pulled the drivers head and found a sever burn between the 6-7 cylinder walls, with number 6 piston scorched and number 7 just starting to scorch. Thankfully, somehow it was just the head gaskets that were affected. The rings were fine, there was no scratching of the walls (evidence of the honing still very visible), and I was able to keep the shortblock intact. I got new gaskets, cleaned and sanded everything and got it built back up... But the question is.. What would have caused this to run so lean? Injectors were working A1.... Bad O2 sensors maybe?? Haven't ran the engine again and haven't ran any diagnostics... figured I'd get some ideas first... any ideas?



'92 5.0l lx notchback

Engine mods:
-bbk cold air intake
-75mm pmas mass air.
-70 mm bbk throttlebody/egr
-trickflow street upper/lower intake
- ford racing 24lb injectors
-trickfow TW 170cc heads
-trickflow .600" lift valve springs
-trickflow 1.7rr's
-trickflow 6.5" pushrods
- comp xe270hr-12 cam
- comp lifters
- Walbro el. 255 fuel pump
- kirban adj. fuel pressure regulator
- meziere el. water pump
-u/d pullies
-good oil pressure and water temp.
-a/c & smog delete.
-all egr components plugged off.

mjr46

pics???

capri debris

I have EXACTLY the same set up as you... minus the electric water pump. It should be working fine, but you should've given it some time to break in if it's a fresh engine. The only problem I have is a bad idle... but when I get it tuned, that issue will be gone. All I can think of is you may have some bad sensors somewhere or you need a good tune. Have you checked for any codes?

cch

Sorry no pics... pistons are covered up since the engine is rebuilt( obviously) but I'll get some pics up on Monday of the gaskets, for what little it's worth.

Capris... rough idle? What maf do you have? I had a C&L 73mm and the new PMAS 75mm. I tried the old C&L first and it caused rough idle with a surge between 1000-1300 rpms and then I switched it out for the new PMAS and it was a automatic fix. No surge, ran perfect.... just some food for thought I guess...

mjr46

EVEN THOUGH mine is back together, I'm waiting on a wideband so if I start to lean out i'LL know right away

cch

ugh... money... the unfortunate reality of life.

And yes... widebands are a great thing.. it's great to know you're running lean... but it's even better to know why

cch

...bump...

92tealcp

I think you should have gone with a set of 30lb inj. Remember 24's are only a small step from the stock 19's. Sounds to me, with a lot of past experience with those problems, from my first new 1987 Fox to my now 9th Fox that you need to up the fuel intake. I tell my customers when they do an HCI change to go with 30lb inj from the start. 24s don't flow that much more than 19s. Your timing was way too advanced also.

cch

30 lbs... really?? I didn't figure my combination was that severe... suppose it would make sense though, I can't figure what else it could be. If that was the case, would the computer still be compatible with the 30's? and then I suppose I'd need to send back my maf and get a newly calibrated one..

92tealcp

You don't need a tune until you get above 42lb's, just watch the FP and timing. There is no need to go past 13deg, above that and you kill the upper mid and upper range of HP and TQ. Advancing your timing only gets you a little more bottom end, but you loose it at the top. Plus with the quality of fuel these days I would be very careful with these settings. I run 92 octain and 12deg. on a HCI setup.