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jcc911 07-21-2011 06:43 AM

Turbo Conversion Initial Thoughts
The good is the car is running well at idle.
The bad, if I try to push down on the pedal, it stumbles, like a fuel related issue.
As soon as I take my foot off, idles fine.
I have not yet had time to get a wideband on it to see where the ratios are and tune it, but hope to this weekend.

Any idea what it could be? I know the description is a little vauge. It is an SC with a 930 CIS on it.
SC fuel pump, SC Fuel Accum, and filter.

Should a Euro CIS have a frequency valve?

JFairman 07-21-2011 08:01 AM

The euro CIS fuel head has no fitting to install a lambda frequency valve and one wouldn't work right on it if you drilled and tapped a fitting in it anyway.

jcc911 07-21-2011 08:12 AM

Thanks for confirming. Any other thoughts? or is it too soon to tell with out finding out wha tthe AFRs are?

JFairman 07-21-2011 08:28 AM

If it is way to lean accelerating above idle then a motor will usually stall or die out in a smooth all at once way with no bucking or misfiring and with no smelly hydrocarbon black exhaust smoke when you open the throttle, and if it's way too rich they usually misfire and chug and buck while trying to accelerate with alot of overly rich fuel smelling black or dark grey smoke coming out the exhaust.

Used spark plugs will be black, sooty, and possibly wet with fuel if it's way too rich and they will be clean and very light colored and the insulator will be almost white if it's too lean.

jcc911 07-21-2011 08:42 AM

Thanks for the info, I have really not had the car running past idle more than ~2 min and I shut it down b/c I was concerned I may be way to far one way or the other.
I did not notice any black or greay smoke, just some on start up and then it quickly clears.

I also have not accelerated it long enough to get it to die, so it may be too early to tell yet.
There also seemed like little throttle response when I would hit the accelerator quickly to try to rev it, or that it was not smooth.

mb911 07-27-2011 03:12 PM

ok couple question
1st you are positive all the plug wires got back to where they need to be?

2nd pull all the injectors and verify they are all working (glass jar etc)

3rd make sure the plunger is not stuck

4th make sure there is no leaks in the cis as to not be able to pull the plunger with vacum

5th WHat it does not run like mine;)

call me if I can help any further

jcc911 07-27-2011 03:36 PM

I was able to get my hands on an LM 1 for the night and at idle the car is @ 12.5 and as soon as I start to accelerate, buy 1100 RPS I am already at 14.5

How is this corrected?


5th WHat it does not run like mine
Well I am not a master mechanic... but seriously your car is bad a** and goes like hell!!

jcc911 07-27-2011 04:08 PM

Throttle response seemed fine. I took it up to ~5500 (still in my garage) and let off. A couple of loud pops, but I guess was running fine.

Cant wait to actually drive it to see where we are at.

patkeefe 07-27-2011 05:57 PM

You likely have a fuel delivery issue. Mine does the same sort of things. I just ran mine tonight for the first time in two months....stumbles, no power on boost at revs. I can make some of it go away with the boost retard control turned up to 3 deg per pound. I turned down my warm control pressure to 34 psi and same thing. It may be ignition, but it;s usually fuel. AFR's were going up a bit, so it may have been running out of fuel.

I had it running pretty good in May. It was colder weather. The SC fueling system is very finicky with ambient temps and a stock fuel head. Shaking out a homebuilt turbo system requires a lot of head banging, I have found out.

sheriong 07-28-2011 05:34 PM

You are obviously running lean, look for leaks in your vacuum system.

jcc911 07-29-2011 06:42 AM

Where are the typical porblem areas for leaks?

sheriong 07-30-2011 10:20 PM

Check the connection at the throttle body, or even actual vacuum lines, may have gotten pinched. Have you checked your FP?

jcc911 07-31-2011 04:23 AM

I hope to get a chance to look at it today. Have to get a can of carb cleaner. FP? fuel pump or puel pressure?

jcc911 07-31-2011 02:08 PM

I pulled my car out of the garage, just a few minutes ago, first time since last October!
When I started it, I had similar symptoms, didn't fire right away, sluggish response, but slowly got better.

While running, too a peek in the back to see if I see anything obvious and noticed this.

The vac line from the WUR to the air box is too long and is crimped? COuld this be the source of the issues?

I am going to pull the IC, shorten the hose and see if that helps change the AFRs or the hesitation when first starting.

jcc911 07-31-2011 02:43 PM

Fixed the hose but no significant change.
Sprayed carb cleaner around the intake, IC connections and did not hear any change in idle.

Took the car "around the block" but did not even get it out of first or past 1800 as the AFRs were in the 17s so I was too hesitant to go any further or harder.

sheriong 07-31-2011 03:56 PM

FP - Fuel pressure. Are you using an adjustable FPR? If so, I would increase the pressure and see whether it changes your readings.

9dreizig 07-31-2011 05:17 PM

It's furel related vacuum leak will cause it to rich!

jcc911 08-01-2011 06:54 AM

What is the best way to check FP? What should the FP be at? If it is low, how is this adjusted. Thanks all.

mb911 08-02-2011 04:52 AM

I have a cis tester you are welcome to use.

9dreizig 08-02-2011 08:58 AM

I'm working my way through this myself as of Saturday. You'll need to check hot and cold control pressure, overall fuel pressure, then fuel delivery rate. First you'll need to get mb911's test setup. And as long as he's delivering it, have him help you run the tests.. as he knows what to check :-)

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