[cobravin]

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with Bosch bypass hooked up the car idles pretty good, air mixture is 14.6 at idle and light throttle but doesn't seem to go richer than around 13 at wot, there is a lean hesitation while cruising at part throttle when you try to give it gas, it stumbles and the wide band reads lean 17-1, then it goes away,

when i disconnect the vac line to the bypass and plug the vac ports the car goes rich with a surging idle that goes from 13 to 10 to 1 air mixture, i have tried resetting the idle and tps with no change

what would cause this surging with the bypass not hooked up, and why would it go away with it hooked up, i thought the purpose of the bypass was mainly to keep compressor surge from damaging the blower impeller, is it normal to have this much affect on idle and air fuel mixture???...Vinny

engine is 5.0 converted to mass air
vortech v1-sc supercharger stock pulleys, bosch 117 bypass, home made 4" powerpipe
ford gt40 y303 aluminum heads
stock cam with 1.7 roller rockers
90 mm lightning maf meter
42 lb injectors no fmu
walbro 286? fuel pump(the big one)
new ford fuel pressure reg 40 lbs unplugged drops to 35 plugged in, my new holley broke and was spitting fuel out
70mm bbk throttle body with new ford tps
explorer intake no egr or smog or cats
new(reman) a9l computer with SCT 4 position chip burned for my setup by fordchips.com

[cobravin]

the discharge from the bypass gets put back right in front of the blower inlet, i even swapped the inlet/outlet of the bypass with no difference, i also tested the bypass(new bosch 110n)it works correctly

i reinstalled the bypass vac line, cause with it unhooked it was surging pretty bad, it would dip in the 10's and a puff of black smoke would come out, so now with it hooked back up its idling perfect at 14.6, but it still runs too lean when i gas it, so i'm afraid to do a full throttle prolonged wot, it shows no codes with the bypass vacuum line hooked up, without it hooked up it shows 42 and 92 (02 rich)

i also rechecked for vacuum leaks by spraying starting fluid everywhere, no change in idle

i also went over my vacuum lines with a vacuum pump, no leaks

i have called fordchip.com many times and left messages with no return calls, the one time, a few weeks ago i did actually speak with Pete i asked him to send the file of the tune so a local dyno guy could just make changes instead of doing a whole new tune, and he said he would send it but hasn't

at this point i would just redo the tune but i need to know if i have a problem with something else in the system

3 things that MAY be important

1) my fuel pressure with the vac line to the FPR unhooked is 45 lbs, its a new Ford(made by bosch)stock FPR, you would think it would be running rich being 5 lbs over the normal 40 lb's

2)months ago i went through all the pins on the computer and did every test i could read about, cleaned my 10 pin connectors, replaced iac,replaced 02's (ford) wiring harness, at that time it was running rich with the vac line to the bypass hooked up but i had no ground to the MAF meter the wire in the harness, ran a wire from the MAF connector to ground and it seemed to cure the running rich problem, but then i got the lean stumble problem and higher than normal air fuel ratio's

3) the engine runs and idles at 220*, it has never overheated, and i don't know if the gauge is even reading right(i will test that though), it has a standard 190 or 195* thermostat and coolant flows at that reading, although looking in the T filler with the engine running and up to temp the water does not gush by, it just kinda drifts by, that may be a separate problem though

with all the testing and problems trying to get this running right i almost wish i would have just put a carb on it and enjoyed the summer, its been on the road since March and i only have 300 miles on it, and most of that testing and worrying whats wrong, very frustrating and annoying ......Vinny

[cobravin]

one of the guys on ffcobra.com (this is a 65 cobra replica) said maybe the blower is forcing the throttle open, creating the surging, that might explain how my vacuum reads 18 inches steady with bypass, but swings wildly without it, almost like someone is creating a 70mm vacuum leak, maybe?

another thing, last night i got a code 96 (fuel pump secondary circuit fault/ high speed fuel pump relay open)for the first time ever, what does it mean, this was after clearing the eec and resetting idle and tps and checking vacuum on the fpr while running,could it be related to that or might it be an intermittent fuel pump, its a walbro 255 in tank, maybe that's whats causing my lean stumble

I'm using a hard wired innovate lm1 with rpm cable and I'm data logging afr, rpm tps,maf and bap,the lm1 seemed to match the sniffer on the dyno,im not sure how to interpret what I'm looking at in log works(the lm1 software) and just haven't had the time to learn about it yet, the only things that seem to make sense are the rpm's and afr, the other things are hard for me to interpret, and I'm not sure if they are set up correctly, voltage wise

the afr idles pretty steady but seems to jump around while I'm driving, from about 16 to 11 with spikes to 19, I'm sure this is an error, or a miss or you'd think it would have blown up by now

timing is at 10* and i think that's where its supposed to be with the chip making adjustments from that base setting, and i am not running an FMU, fun fun fun........Vinny

[cobravin]

also i have a digital fuel pressure gauge in the cockpit that i can see when I'm driving, its hard to keep an eye on the road, and eye on the air fuel meter and an eye on the fuel pressure at the same time but if i remember right it reads about 36 lbs driving and goes up as i get on it, the fpr is a new ford(bosch)and reads 45 lbs with no vac line on it( it used to read 40 a few weeks ago)if i pull vacuum on the regulator with a pump, while running, the fuel pressure goes down so i assume its working ok

is there a way to test the fuel pump to see if its cutting out or not supplying enough fuel?, would my fuel pressure drop under boost and rpm if it were not up to the task, its a new walbro 255 but you never know.......Vinny

[cobravin]

everyone stumped???

[sweet88gt]

Ok, as far as the reading rich and lean with the LM-1 I have encountered the same problems. It will idle near 13.xx-14.xx. This is at idle and jumps around a bit but never higher or lower than those numbers. At part throttle I will get the same general ups and downs from 13.xx-15.xx. When declerating you will always read a high number as being lean. This is because the fuel has been reduced and the motor is basically a large fresh air pump during decleration. I have similar readings and have yet heard any ping and havent blown the motor yet. Thats not to say either of us are in the right ball park.

The Walbro pump you have, is it a high pressure or high volume pump? Walbro makes 2 different kinds of 255 in tank pumps. I have the high pressure with 42 lb injectors running 43 psi fuel pressure with vac. line plugged. I have more than enough fuel for the horespower I'm making.

With the temp your car is running may have an effect on the computer. Has it always run at this temp, before and after the blower?? At a certain temp the computer will retard timing to prevent detanation. Double check the water temp to make sure.

The surging idle is a pain with my car for sure. I have modified the idle air motor with a dremel tool and that seemed to help. I used a "band-aid" idle air motor spacer plate to rid myself of this problem. I could not restart the car because of a rich condition at start up and turned the screws all of the way out on the spacer and cleared the start up problem and surge for the most part.

How did you fix the mass air sensor ground?? I mean where did you hook up this wire and why did you not have a ground to begin with?? I have a feeling this is the root of your problems but I'm no genius for sure. Hell I'm still trying to get mine to run perfect. I dought that will ever happen.

Try the innovate web site for more information on the LM-1. It will help you understand the features. It took me awhile to configure the rpm converter. I am almost positive that you will not be able to datalog with the stock BAP. If your car is eqiupped with mass air they refer to the same sensor as a MAP sensor. You will need make sure there is no vac line going to this sensor with mass air equipped cars. You will also need a 3 bar Map sensor (GM or other) to datalog boost pressures. The Lm-1 will not sense the Ford Map. If you did datalog boost your graph would look like a square wave. Innovates forum will help with this also.Hope this helps.

[89Notch]

Why would you disconnect the bypass? Reconnect it and go from there...