I have started and ran this motor several times. It will run real nice for a while (pretty much perfect) and after a while it will start acting up. It wont stay idleing, runs rough, etc, etc. When it does this, I check the plugs and they are always black as can be. They dont look real wet (maybe a little) but they are just black. You can wipe the black soot off of them real easy.

I have gone through 3 sets of plugs trying to get this thing running right. Whats the deal?

I was wondering if the PCV system could havea anything to do with this. Right now I dont have any breathers or anything on the valve covers. Both holes are just open on the valve covers. Will this have any effect on it?? I have no clue. I am wondering if AS&M funked up the computer calibration (adding too much fuel) when they recalibrated it for the 30lb injecters and the fast-burn aluminum heads.

What else would cause this?

ANy help would be appreciated....I have got to get this thing on the road because my other car (the 88 formula) died and I have been without a car and need to get this thing going. Thanks

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L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.

 

Lay off on the fuel pressure, or switch to hotter plugs.

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"Question with boldness even the existence of a *** ; because, if there be one, he must more approve of the homage of reason, than that of blind-folded fear."

-Thomas Jefferson

 

Joe, that would be my guess. This is why I feel modifying the SD 7730 is a better route to go, because you can easily modify the eprom and monitor the results with a scan tool. You can't do that with the GM computer.

Basically, you are at the whim of AS&M like many guys who bought a Miniram and then got TPIS to burn their eproms for them. Possibly worst off, as TPIS at least has years of feedback and experience with different combos where as your setup is probably not very common.

Does that EFI even use an O2 sensor? And if it does, it still doesn't mean it is calibrated correctly, especially in WOT when you don't use the O2 sensor for fuel corrections. They may have Power Enrichment (ECMers term for WOT) engaging very quickly so you would rely solely on AS&Ms calibration.

Want to consider converting to SD? If so, pop on over to the DIY Prom Board and we'll see what we can do for you. You can also drop me an e-mail too.

 

The MEFI3 computer does not use an o2 sensor. Just the usual speed density stuff.

I think I may have found something out. I didnt have the ignition coil mounted and secured at this time. It was resting on the intake. I think I saw it arcing against the intake. I think this could cause the plugs to not fire or just get burnt up.

Another thing....In the ram jet service manual, it says to set the base timing at 10 degrees. Well, I have changed the heads, cam, and injectors and it seems to run a little better when the timing is up around 12-14 degrees BTDC.

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L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.

 

Good to hear you might have figured it out!
Let me know if it works...

I just wanted to remind you to update your new email address in this forum and also to send it to me if you will.
Talk to you later.

 

Joe, the lack of an O2 sensor means the Ramjet's MEFI3 MUST have the correct tables for ALL load/rpm ranges. You don't have the benefit of the stock 7730 SD ECM use of the O2 sensor to correct at part-throttle.

If the RamJet's fuel tables are off, then you get no correction from the O2 sensor (in part-throttle) and if the tables are too rich, then you'll run too rich - all the time.

 

I called AS&M today and they told me that they screwed up on the computer. They guy accidentally programmed that MEFI3 computer the way that they calibrate their computers which incorporates an intake air temperature sensor. Well, the ram jet doesnt have an intake air temp sensor so he said the computer is basically giveing the motor about 15% too much fuel at idle..thus, fouling my d@mn spark plugs and causing it not to run right.

Im sending the thing back to them and they are fixing it free of charge (of course). It sucks that this happened though. I could have been driving this beast around right now.

By the way...Ill keep everyone posted on how it runs too. Supposed to be around 430HP so it outta go. Later

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L98, 3.27 9-bolt, Hooker shorty headers, custom 2.5inch Y-pipe, no cat, 3inch 2chamber flowmaster, JET AFPR, Ported MAF, Best ET: 13.86 @100mph. 1.99 60'
17 inch ROH "ZS" wheels. 17x8.5(front) and 17x9.5 (rear). Firestone Firehawk SZ50s. 245/45/zr17s and 275/40/zr17s. T56

On the way... Radar Blue 89 Formula, T56, Ram Jet 430, Ram Air, 17inch ROHs.

 

No IAT/MAT? If it is possible to add an IAT/MAT sensor to the MEFI3, I recommend that you do it. That's 2 GM controllers (MEFI3 and one of the GM TBI ECMs) that don't utilize an IAT.

I find ambient air temperature has a great effect on my Injector Pulse width. Mine are at 10-15% longer in the cooler part of spring/fall than in summer (I try not to drive my car in the winter). I personally feel GM should have used an IAT/MAT, especially since it doesn't have an O2 sensor.

But at least AS&M are reprogramming it for you. You may just want to check your plugs during different seasons to ensure it isn't overly rich in cold weather or lean in summer.

[This message has been edited by Glenn91L98GTA (edited December 10, 2001).]

 

And maybe it's just the wrong timing tab, Joey! LOL...raised from the dead to say it's JUST BEEN FIGURED OUT