Happy Fathers Day to ALL

[csx4910]

First off happy father's day to all! May your fathers day be filled with Bad ties, gifts you have no idea what they are etc. Father's day brought me a Smith and Wesson Model 629 44 magnum with a 6 inch barrel for father's day! ( My wife knew I had been wanting one for a while)

On a bad note, it also brought me more problems with my cobra after hesitation under acceleration, I put it down to it being a relatively cool morning and only having half a tank(my fuel injections does odd things and gets cranky if I am under a half a tank) so I went to fill up with 100 octane to mix 50/50 with the 91 crap we have here in Phoenix.

Well the hesitation went away and it was running fantasic until I got off the freeway and pulled up to the light. I noticed it was idling at about 1200 instead of the 900 -1000 rpm, then dropped down to 900 and died. It took 20 tries to get it to fire again and ran good until the next stoplight and did the same thing, this time taking 30 tries it get it started.

Any ideas on the funky idle and then dying after it had been running so much better with fresh juice in the tank?

[Danr55]

Chaeck your fuel filters first... After that, take the new 629 to the Rousch motor and get yourself a good FE and be happy!

Seriously, my car did the same thing just before the ignition box died. New ignition box, problem went away.

[Bob Broberg SPF667 460BB]

Thank you Ron. Here you go again? Keep it simple. It's either fuel or spark and you can eliminate one or the other. If fuel, check filter. I'm sure you have a pressure gauge. If spark check spark jump color at the plug tip. MSD box? Their website has step by step procedure to follow to diagnose.
Good Luck
AZ Bob

[Slither]

csx4910, if you want it fixed right and for a fair price, call Tom Barnard at Speedway Classic Cars in Las Vegas. Tom's business was called Tom's Motorsports until he was bought out. He still runs and operates the business. He has countless hours working on, building, repairing and tuning Cobras. At least give him a call at (702)651-0708. I know it's a little far from home, but...

[csx4910]

I might look him up. I am getting quite tired of driving it once or twice and something else breaking. You would think at 1800 miles it would be "sort out" as everyone calls it. Last time we were investigating the hesitation under acceleration and the distirbutor failed. Got it back from that being fixed and the fuel gauge being stuck on full and after 2 drives the fuel gauge is stuck on full and now it is idling funny and dying sitting still.

[csx4910]

Anyone know if Bob Rheam is still in business? He had the magic touch with my fuel injection in the very beginning before Roush finally sent their people down to phoenix.

The hesitation is intermittent and goes away when I put the racing fuel in it or when the car is warm. It has been happening off and on since the car was new and no one can seem to find out why. The idling high and then dying is a new one. While I was told never to trust the fuel gauge, it would be nice to have one at least partly working and I have already paid someone to drop the tank, move the float around etc, only to have it do it again after driving the car twice.

[Bob Broberg SPF667 460BB]

Here's Bob's latest business: Imagine Injection - "Home of Quality High Performance Fuel Injection Systems"
I don't know if he still has B & R Automotive on McDowell Rd. anymore.

AZ Bob

[csx4910]

I went out last night and it fired right up but still was idling about 1200 rpm. Any chance the mixing of higher octane into the system(although I have done it many times before) could of confused the computer EFI management system?

[Danr55]

Chances are changing octane would not confuse the coprocessor. There is a better chance that you have a clogged fuel filter or a malfunctioning feed or sensor somewhere. What keeps fouling the float in the fuel tank?

[csx4910]

I have no idea. I wouldnt think even something floating in the tank would bother the float too much but something is

[cobish]

Byte the bullet, rip it out, and replace it with a Holley
Roush does not use FI on his Nascar enterd cars, they use a Holley,
dual ingniton, for coures this my opinion.
Good Luck

[Danr55]

I was wondering if something in the tank was fouling the float mechanism. If it's fouling the float it's go to be fouling the injectors. Just a thought..

[csx4910]

So the only way to know is to drain the tank, drop it and see if there are any body pieces floating in it then put it back together and fill'er back up?

Other than 5 gallon buckets, any other suggestions on how to save the fuel and how to strain the fuel or flush the $100 I spent on race fuel down the toliet.

As much as I have gotten to love Charlie and Dean, Since I just paid them to do this and it didnt work with the fuel gauge or the hesitation, I think I am going to give this one a try on my own or take it somewhere else

[csx4910]

What are the chances of the foam in the fuel cell breaking down and getting in the tank? Forgive if that is a stupid question but is it possible.

[Danr55]

Ron, There are lots of reasons why a fuel gage won't work. The first one I think of is the reason mine has never worked right. The gage and the sender have to operate at the same ohmage. That is the resisitance created by a full tank has to be compatible with the resistance rating of the gage. If, as in my case, you have a US built sending unit in the fuel tank and a British built gage in the dash board, you'll never get the two to be compatable because they operate on a different resistance. So ignore the fuel gage and set the trip odometer each time you fuel. That's what I've done and it works fine. As for the hesitation, ... it's pretty normal for an engine to hesitate when it's cold or using fuel that is under rated for the compression of the engine. What is the compression ratio for your motor?

[csx4910]

9.5:1. I believe others have always run 91 octane in these motors without problems. I just know hte hesitation goes away and it feels like I picked up quite a few deat of the pants horsepower with 100 octane in the tank

[Danr55]

100 Octane will always give you a boost. I personally like the 110 leaded fuel but can't afford $6.00/gallon. So I use 91 pump gas and accept the lowered performance. I'm running about 10.3:1 compression. So, if you are bothered by the hesitation, there are a few things you can try. Do you know where the timing is set at idle? Try advancing the timing a couple of degrees at a time, up to about 16 max at idle. Performance should max out about 14. At least that's been my experience.

[SandyC]

Originally Posted by csx4910

9.5:1. I believe others have always run 91 octane in these motors without problems. I just know hte hesitation goes away and it feels like I picked up quite a few deat of the pants horsepower with 100 octane in the tank

Ron,

I believe the CR is 10:1, but I could be wrong.
http://dealer.webmakerx.net/Images/S...te_engines.pdf
go to page 2 of the PDF brochure.

The 511 owner's manual says:
"The Roush EFI engine was designed to perform with 91 or higher octane unleaded fuel. Please use the highest grade of fuel available at the time of fill up to ensure the best performance out of your Roush Performance engine."

BTW, there's a new version of the owner's manual and installation manual for the 511iR with the Accel/DFI system. I think I have your email address and will send you an email to give you further info. Big emphasis now on making sure your engine is not overheated:

"Your engine is equipped with a 180° Thermostat. You are required to provide an engine cooling system that will maintain a maximum coolant out temperature below 220°F under all operating conditions."
(red type above on the emphasis is there in the manual too)

The 180 degree thermostat is a change, it used to be a higher set-point thermostat, 200 degrees I think. Mine was changed out to the new lower setting thermostat. So far the maximum temps I've seen driving in 100 degree F OAT was 85 deg. centigrade (185 deg. F), I always use the auxilliary fan when temp is 80C or higher and it seems to hold it there ok. I asked Charlie to really go over the cooling system with a fine tooth comb. He sealed off some areas where he found air could sneak around the radiator.

My engine idles at 1000 rpm which is right on with the owner's manual. At very high OAT's when getting off the throttle the engine will immediately drop down to about 1300 rpm then slooooowwwly drop down into a 1000 rpm idle. If this happens a quick blip of the throttle drops it immediately down to a nice 1000 rpm idle. An occassional liveable quirk in my opinion. I don't want to take the chance and mess with fuel/temp curves to try to deal with what I consider to be a minor thing. So far no hesitation issues.

In my experience the only way to tweak the EFI is to get Roush to do it by having the local shop download data from the ECU and upload it to Roush along with a detailed description of symptoms for analysis by their experts, and then have Roush send new data to the local shop for loading into the ECU. Sounds easy but remember, this is Roush customer service we're dealing with so good luck. I had the local EFI guru try to tweak mine once, with Roush's approval since it was under warranty, and he only made things worse. Roush ended up having to analyze the problem and fix it.

That was when both our engines were new and we were having EFI problems Roush put their EFI expert on a plane and sent him out here to troubleshoot. He rode along in the passenger seat with a laptop on his lap that was wired up to the ECU. Tweaks were made to the curves under real-time, real-world driving conditions in the actual car. Now that's the dream way to fine tune an EFI system.

My car has a Fuel Safe racing cell (as does yours?) that uses an electronic quantity sensor that is almost completely unreliable. To make it work it seems to need recalibrating after about every second fill up, which is not practical.

Pegasus - Fuel Safe Fuel Level Sending Unit Set-Up

So I always use the trip meter. Let me know if you come up with a fix.

[csx4910]

I stand corrected on the CR. I could of sworn that I was told it was 9.5 but according to Charlie it is at least 10:1 or higher. I have had the 1300 blip the throttle and it go down to 1000 but in this case when I tried it wouldn't go down and then suddenly coughed and died. Acted like it as flooded when it wouldnt start. Vapor lock maybe? I am stabbing in the dark

[tin-man]

For what its worth guys Roush advised Erick Voss of Voss Performance they are working on developing a new program for the 511 IRFE that has an idle of between 800-900 rpm. This should eliminate the casue of my grabbing effect that I talked about, but not sure if this would help in your case since you have manual, correct? Just thought I would throw this in. tin-man