car is surging at idle and missing thru mid range

mekessler · Post by **mekessler** » Tue Jul 17, 2012 4:23 am

Just installed a 2.1 kenne bell supercharger on my cobra and its goin crazy now. It has a trickflow throttle body and bbk egr plate both are 75 mm. Has 42 lb injectors with a matched 76 c@l mass air meter with stock sensor and factory air box with a k@n filter. Has stock fuel regulator with a kenne bell fuel management unit. I've adjusted the tps and checked fuel pressure and engine compression. All is set right but its still surging and missing thru the mid range and stops pulling all together around 5500. Engine is all original other than a E303 motorsport camshaft. I'm out of ideas anyone else had this problem??

Post by **1993cobra** » Tue Jul 17, 2012 7:19 am

what is the timing set at? what ignition?, does it have a spark retard? is it popping any?

93 Venom · Post by **93 Venom** » Tue Jul 17, 2012 8:27 am

1993cobra wrote:what is the timing set at? what ignition?, does it have a spark retard? is it popping any?

I agree, sounds like timing. Did you have it tuned after you put the supercharger on? If you didn't, I would take it to get tuned at a good shop.

mekessler · Post by **mekessler** » Tue Jul 17, 2012 11:13 am

I backed the timing back from 14 to factory 6 because of spark knock. Plug gap was reduced to .035 and ignition is all factory except for new Ford racing cap and rotor and wires. It's not popping and but putting out the black smoke. I haven't had it tuned other than setting the tps at .99 and throttle around 1,000 hard to tell with it surging thou. Fuel pressure is 34 and 40 when it speeds up with a 190 Ford racing pump.

hnkstang50 · Post by **hnkstang50** » Tue Jul 17, 2012 11:16 am

C n l meters use a calibration tube and are notorious for having issrs with poor calibration. Are you supposed to use the stock cobra maf in them? I would think your problem is with this meter/tune

mekessler · Post by **mekessler** » Tue Jul 17, 2012 11:27 am

Yes it just came with a housing and tube that bolts in with 2 Allen bolts and install the factory sensor on top. It's a neat simple set up if you want to change to different size injectors. I'm kinda thinking it could be the problem to. I swapped my sensor from my GT with no change in it. Kinda thinkin its calibration is wrong.

buddha · Post by **buddha** » Tue Jul 17, 2012 12:16 pm

Ditch the C&L and go with a Pro-M calibarted for the 42's or a SCT with a chip. The C&L's are way to hit or miss. They require a lot of monkeying with them to get to work even half right.

Bump the timing back to 10 degrees and just keep your foot out of it and the RPM's down until you get the MAF and tune sorted out.

mekessler · Post by **mekessler** » Tue Jul 17, 2012 8:21 pm

Does the pro-m need to be calibrated for cold air or superchargers etc?

buddha · Post by **buddha** » Wed Jul 18, 2012 10:12 am

http://promracing.com/home-page-bestsel ... ation.html

mekessler · Post by **mekessler** » Sat Aug 04, 2012 9:46 pm

Got my pro-m mass air meter installed and ditched the c@l and idles and revs great.. Gonna have to take it for a run and see how it pulls. Put my timing dead on 10 curious to see if it still spark knocks or if I'm gonna need a timing retarder. How's yours budda with the kenne bell? Have to run aftermarket timing setup or tune the computer?

hnkstang50 · Post by **hnkstang50** » Sun Aug 05, 2012 9:33 am

Did you pug in a colder heat range plug. If not I would to one stage colder also gap at around .035 to help with spark. I would set timing to 6-8 degrees just until you get it all figured out. Or lock it at 20 and keep the jumper out so the computer has no control... again just tempory till you get it all running good.

mekessler · Post by **mekessler** » Sun Aug 05, 2012 9:59 am

I put in a set of autolite 764 in it gapped at .035 they are supposed to be one step colder than factory. I think I'm finally getting in the right direction. Will try that on the timing if it starts knocking again. Never really got to feel what its gonna do for having to let out of it.

buddha · Post by **buddha** » Sun Aug 05, 2012 12:15 pm

Good to hear. Funny how the right part makes all the difference.

How much boost are you pullied for? I'm guessing between 6-8 psi? In any case, you could just go with a MSD BTM to pull the timing for you. Nothing high tech, but they work for mild combinations like yours.

mekessler · Post by **mekessler** » Mon Aug 06, 2012 1:48 am

It's supposed to be 8 lbs never seen the gauge go over 7 lbs thou but never got to stay on it either. That's what I was hoping to hear because its 4 hrs to a dyno shop. I'm thinking that's all I need now is the timing backed up in high rpm. Will find out as soon as the roads dry.