icsmike

Great, just great. I as moving my car back in th garage after some friends left and i turned the key and it cranked about 1 turn and went "POP" super loud not like the usual intake backfire. It would not start so I pushed it into the garage and popped the hood. Bad news..... I found both of the intake collectors had blew off of the intake and they had made 2 nice indentions in my newly painted car hood. !!!!!! OMG I AM SOOOOOO PISSSSEDD!!!!!.

this sucks, I have to wake up tommorow sober and remember this crap. I wonder if it was form leaky injectors? It was cold when I went to start it and I gave it a bit of gas a it went BOOM. Grrrrrr.

Has any one had this happen before? The AFM and screen were untouched it was just the collectors that blew off, and I havent put it back together yet to see if anything else got banged up. What about the hood dents? they made nice pings and made the paint crack, can they be fixed too? Thanks.

Mrmerlin

if you can find a rolling device you may be able to roll the dents out but you will have to have a hard piece of metal under the hood , so it means removing the hood liner, Bummer about your backfire. if you get this far and your happy with the smoothened hood then add some clear to the cracks and wet sand it down and add some wax

icsmike

Thanks, i hope to talk to My body guy tomorrow. Hopefully he can make it painless for me and my car.

PorKen

I've never had this happen, but I've seen a couple of threads about it, with no determinate cause, AFAIK. Bummer about the dents.

What was the weather like?

How old are the plugs/wires/caps?

You said you pressed the gas pedal when starting?

icsmike

Thanks Porken for being here/Doc! heheh.... I started her up and rolled it out today about 25 feet, no warm up time. Temperature was muggy 85 and 85% humidity. After we were done hanging out i went out to start the 928 and pull her in and when I started cranking I pushed th pedal down to make that cool "RoowhH' sound.... but this time it made a pop.

Oh the wires and caps arent that old, maybe 3-4 years. But it always had a thing about if you startrd it without pushing the pedal down it was "lazy" but if you pushed it down it got busy quick.

JHowell37

I did it once on my '85. I sprayed a bunch of ether down the intake and had two of the plug wires crossed. It didn't dent the car because the hood was open but it did dent the refrigerator door when the end flew off. The other side took the exhaust test port with it.

Brad W

That should be covered on your insurance. Get some pics and make a claim. Thats what they are there for, so use them. Most collector car insurance is $0 deductable......

LightStriker

There a good number of thread about this... Even that guy with his hood open and who found his intake stuck in his fridge's door.

From what I understood, this problem seam to happen only after they added computer control ingnition. For some reason, the computer get a brain fart and ignite a chamber that still has the port to the intake open.
Only appear to happen at startup.

Temekun

I did itwith 2 plug wires crossed and now have the fancy hood dimples to contend with myself. It did it at start up and may been from some fuel in t he intakes somewhere and a nicely time firing into the intake. I needed to replace the old intake rubbers and I had red silicone ready to go. It also gave me great access to the valley to clean out the decadesof goo, gunk and mouse bits. Also replace a bunch of old vacuum lines while I was in there.

Tim

PorKen

Intake backfire is usually from an overly lean mixture, often combined with over advanced ignition timing? (Spark fires while intake valve is still open.)

If you push on the pedal even slightly, the ignition advance at idle rpms goes from 10°+ to 20°+! (Or if the throttle body idle switch is broken or disconnected, eg. bad extension connector.)

Mike has running problems, probably from vacuum leaks, perhaps an old MAF too. So a combination of a (drunken) lean start, with 20° advance = intake backfire.

Moral: don't touch the pedal while starting!

My 86's both seemed to take forever to fire while starting, compared to my '81. I think the EZ-F waits for a really good signal from the crank sensor before activating the LH, which then turns on the fuel pump.

6mil928

Any pics?

icsmike

Soon.....

icsmike

Thanks for your info Ken, I have a rebuilt MAF from Roger so0 its ok. I never knew about the iginition timing advance from the throttle, wow...or "woops". I took it all apart and found that the MAF and the middle (the large) intake T had blown out of its place but no visible damage is noticable. I did find all kinds of nasty, brittle vacuum lines, they broke just from me touching them. Most of them are on the drivers side by the brake MC. I also found a good size pool of gas in the unit that the maf hooks to in the valley. Do i need to address the injectors or just o-rings while I have it out?

LeRox

wow that sucks..

ken,

so this can be induced with the right sequence of events?

6mil928