First run- HUGE dissapointment

[cmcfaul]

Had a heart attack last night. Went for the first drive after my first rebuild and it ran like ****. Did not think it would make the one mile home. Went to bed thinking I was going to have to take it all apart again. Can you imagine. Then it hit me in the middle of the night (literally 4:00 AM). It's running lean because of the new cam. So this afternoon I turned the linkage to the MFI three turns to enrichen the whole throttle range and bam, it runs nice and smooth. Pulls hard all the way to redline. I think the MFI still needs to be dialed in but thank god it does not need to be taken apart again.

Oil pressure is exactly to spec (10 lbs per 1,000 rpm's) and it does not leak a drop.

At any rate she runs really good. I think I can get a few more HP when the MFI is dialed in.

Chris
73 911 E

[Daviboy]

Chris,
Congrats on getting her running. I have not had the chance to give mine a first run yet just the cam break in and while the engine sounded great I am also considering all the scenarios associated with first run, will she pull as expected where will the power come on (964 cams in SC) will she be better etc etc.....

[SCOTITUDE]

I love those fixes. glad to see I'm not the only psycho that has middle of the night revelations. I cant tell you how many times i have had the solutions pop into my head while I thought I was sleeping .

[flat6pilot]

I hate that feeling.

Glad it turned out for the best.

Enjoy.

[cmcfaul]

Thanks all,

The 20 min cam break in was fine. Seemed to run great. Once I got it out on the road for the first time I was positive there was a major screw up somwhere.

Drove it to work this morning and no issues nice long drive and took it to redline a couple times towards the end...No problems, though I think there are some horses missing in the current MFI settings. Will get that fine tuned in the days ahead but no big deal.

Very happy,

Chris
73 911 E

[304065]

Originally Posted by cmcfaul

Thanks all,

The 20 min cam break in was fine. Seemed to run great. Once I got it out on the road for the first time I was positive there was a major screw up somwhere.

Drove it to work this morning and no issues nice long drive and took it to redline a couple times towards the end...No problems, though I think there are some horses missing in the current MFI settings. Will get that fine tuned in the days ahead but no big deal.

Very happy,

Chris
73 911 E

Let me guess, no throttle response either, right? Classic lean MFI condition.

The move is to richen the mixture way up, as Ed Mayo said in last month's Panorama, "the factory settings are no longer applicable since they stopped putting Gas in our Gas." Ultimately you need an LM-2 or other wideband sensor to really know what is happening, but I guess what I'm saying is the rule of thumb, 3-4-5-6 works pretty well- 3-4% CO at idle, 5-6 at part-load. Those correlate to some pretty fat AFRs but again, the old factory stuff where you could run a lean mixture for fuel economy stopped being useful in the early 1970s. With oxygenation additives and ethanol the stochiometric mixture is less than 14.7 to 1 anyway, probably closer to 14.1.

Ahh, but the pundits will say, "there is no objective 'setting' for the MFI pump, you would always tune it using AFR and therefore shoot for a target number, it doesn't matter how many clicks on the rack." To which I answer, true enough, but CMA says you start with the adjusters in the middle of their range, and then ultimately you shoot for a best power mixture that is someplace richer than where you would target given 100% octane fuel.

Fun with MFI. . .

[cmcfaul]

Yep, had the MFI rebuilt buy Gus 5 years ago and have not touched it since. What I did yesterday was a quick, get it running, fix (just lengthend the linkage to the MFI pump to make the whole range richer. It is hard to start now as it's getting too much fuel at idle. Need to back out the linkage adjustment and dial in a couple clicks of enrichment on the pump.

Or just bring it to someone who knows what they are doing and pay to have it done.

Chris

[Mark Henry]

Compared to the price of a leaned out blown engine a Wide Band O2 meter is cheap insurance. Tells you if you have a lean/rich AFR (air/fuel ratio) instantly.
Get one and you should be able to tune it for correct AFR yourself.

[cmcfaul]

I hear ya. Plan on borrowing one to see where I am and how accurate the seat of my paints method is.

Minor set back. My ignition switch is toast. Third one in a year....whats up with that? High Torque starter should not matter. Think I just got two bad ones.

Chris

73 911 E