rough engine

[BAD ASP]

I have a 408w with a large turbo. The engine is FI using MSD ignition and coil. The distributor is a stock Ford and I'm using a Fast sequential bank to bank ems. The injectors are 83 lb.The problem is only between 2000 and 3000 rpm. The engine misses and hesitates but you can push through it. The problem is that the rpm range is right at cruise in traffic.When cruising the engine is breaking up and popping a little. It's much more noticeable to me but I had a techie riding with me checking my ems with the laptop and he says all is good. I've changed the plugs and they showed a little rich but not bad. The A/F is right at 13.5. My gut says its ignition because the fuel pressure stays at 60 lbs and I can hear the pump.... it doesn't break up at all. Could it be an injector not spraying at the rpm or is that in the ems.... This condition is somewhat intermittent but I'd call it 80%. It also doesn't matter cold or hot.
Any thoughts will be appreciated.

[undy]

Originally Posted by BAD ASP

I have a 408w with a large turbo. The engine is FI using MSD ignition and coil. The distributor is a stock Ford and I'm using a Fast sequential bank to bank ems. The injectors are 83 lb.The problem is only between 2000 and 3000 rpm. The engine misses and hesitates but you can push through it. The problem is that the rpm range is right at cruise in traffic.When cruising the engine is breaking up and popping a little. It's much more noticeable to me but I had a techie riding with me checking my ems with the laptop and he says all is good. I've changed the plugs and they showed a little rich but not bad. The A/F is right at 13.5. My gut says its ignition because the fuel pressure stays at 60 lbs and I can hear the pump.... it doesn't break up at all. Could it be an injector not spraying at the rpm or is that in the ems.... This condition is somewhat intermittent but I'd call it 80%. It also doesn't matter cold or hot.
Any thoughts will be appreciated.

Better get that A/F between 11 and 12 before you melt the tops off your pistons.

[BAD ASP]

undy....... I checked the A/F and at cruise it is 13.5. On hard acceleration its at 11.0 - 11.5. My engine is rough when cruising between 2 and 3 thousand rpm. Like I said you can push through it but for cruising its not right.

[xlr8or]

Is this a new condition? Was it ok before? Perhaps your plug gaps are too big. Are you in boost at that speed? Where is your timing at in that RPM range? Boost needs to have a little less advance and less plug gap so you don't blow out the spark or cause detonation.

[undy]

Originally Posted by BAD ASP

undy....... I checked the A/F and at cruise it is 13.5. On hard acceleration its at 11.0 - 11.5. My engine is rough when cruising between 2 and 3 thousand rpm. Like I said you can push through it but for cruising its not right.

sorry.. I took it that the 13.5 was at WOT..

Dave

[BAD ASP]

Originally Posted by xlr8or

Is this a new condition? Was it ok before? Perhaps your plug gaps are too big. Are you in boost at that speed? Where is your timing at in that RPM range? Boost needs to have a little less advance and less plug gap so you don't blow out the spark or cause detonation.

The condition is relatively new. I think its been there for awhile but it is becoming worse. I noticed the popping from the exhaust while cruising about 500 miles ago but attributed it to the ems. I get popping when decelerating and I've been told that the older fast systems don't do a very good job of fuel management under deceleration.

I am only running 7 lbs of boost for street driving and the boost isn't really coming in until around 3500 rpm. My timing is about 32 degrees. Plug gap is 30. I'm also using c116 now usually c110 so I'm not worried about bad gas or detonation from low octane.

[undy]

If your problem is between 3000 and 3500 rpms and your boost comes in at 3500 then this appears to be a transitional problem. You said you could "push through" and get by the problem. When you come into boost, about 3500 you go into an fuel enrichment process. Could there be an extreme lean condition between 3K and 3.5K?? That could manifest itself by the symptoms you described. When you come into boost, about 3.5K, you get that much needed fuel. Just a thought...

If your plugs are gapped too far then you would be more prone to encounter the problems under boost, vice part throttle. The dog doesn't seem to hunt.

Dave

[Jerry Clayton]

have you been running leaded gas?????We constantly see computer controlled engines that have have leaded fuel run contaminating O2 sensors which then throws off the tune. I would suspect in your case that the fast system thinks everything is alright because of a bad sensor

[BAD ASP]

Thanks for your continued input. My engine seems to perform fine under WOT or hard acceleration. The problem is that between 2000 and 3000 rpm, while cruising, the engine is stumbling. So for example, if I am driving in normal traffic situations such as between stop lights and I am cruising in third at say 2600 rpm the engine is stumbling slightly. There is a noticeable popping through the exhaust but the parameters are good on the lap top. Unfortunately it is beginning to feel like troubleshootin 101.......... ie., start replacing parts until the problem goes away.........

Again the problem is not all of the time but say 80% and it doesn't matter if the engine temp is cold or normal.

Incidentally, thanks for taking the time so early in the A.M.

[BAD ASP]

Originally Posted by Jerry Clayton

have you been running leaded gas?????We constantly see computer controlled engines that have have leaded fuel run contaminating O2 sensors which then throws off the tune. I would suspect in your case that the fast system thinks everything is alright because of a bad sensor

Jerry, I have not been running leaded gas. For the most part its been c110 and sometimes c116. If I use pump gas its strictly shell premium and then I don't push it too hard.
My first thought was the O2 sensor but I had access to another new one and installed for a short trip...same results so I switched back.
For right now I have access to another identical fast ecu which I am going to swap out. If that doesn't cure it then the next is to swap out the injectors. I am curious if the msd 6al might also be intermittent.....

[Jerry Clayton]

Seems to me that those are leaded fuels-----if from VP

Give Corey a call 630-532-4052 he wants to know if you can email the tune files and data logged info from the fast so he can look at it for you???

Jerry

PS Corey says the oxygen sensors on the fast systems are calibrated to the specific box code you can't just swap them back and forth they won't read correctly.

[BAD ASP]

Originally Posted by Jerry Clayton

Seems to me that those are leaded fuels-----if from VP

Give Corey a call 630-532-4052 he wants to know if you can email the tune files and data logged info from the fast so he can look at it for you???

Jerry

PS Corey says the oxygen sensors on the fast systems are calibrated to the specific box code you can't just swap them back and forth they won't read correctly.

You're right Jerry... they are from VP and I didn't think about them being leaded. I will get those tune files and logs and then give Corey a call.... thanks.

[CHANMADD]

My thought on this.... Could it be that your wastegate is not functioning smoothly at that RPM or that it is fluctuating. Maybe a pill in the actuator line??? Turbo's and all the related plumbing could very well be your problem.
Funny blow off valve??

[Sharroll Celby]

MAYBE a fuel "blockage" that is fine up to the 2000-3000 RPM range, is partially blocked at 2-3000, (hence the stumble), but higher RPM "blows past" the obstruction?

What conditions are your fuel lines?

Just a WAG.

[BAD ASP]

Originally Posted by Sharroll Celby

MAYBE a fuel "blockage" that is fine up to the 2000-3000 RPM range, is partially blocked at 2-3000, (hence the stumble), but higher RPM "blows past" the obstruction?

What conditions are your fuel lines?

Just a WAG.

I've got 60 lbs pressure to the FI logs, the plugs aren't showing lean on any cylinders. The fuel lines are stainless hard pipe to the regulator.
Hopefully I will be doing some work on the car tonight.
I'm in the construction industry and we're slammed with work right now..... so it's been hard to do any wrenching this week.
Thanks for the ideas guys. I'm noting all of these for this weekend.

[RICK LAKE]

BAD ASP Which box are you running? The old Speed pro, the Old F.A.S.T. box. There is a problem with them when running Large injectors bigger than72 lbs with low ohms. The drivers start to break down from the amperage loads, or duty cycles if you like. You could have the 4 injectors dropping out. Need the 6 digit number from the box for what you are running. 122131? You might need to go to a XFI box. I have had a couple of problem with the BOX. The new box has traction control built in. With the power you are maken, this might be a help. If you are on wide band O2, NO LEADED GAS. Is your are tuned with the Alpha N or the other way? The only fuel problem I could see is if the regulator is not upping the pressure when boost comes on. What is the ratio of boost to pressure on your regulator? 1/2 psi, 1/3, 1/5, 1/7? You should also have an LM-1 sensor on this motor to compare O2 readings. EGT is also not a bad extra. What ignition system are you running? You said the motor is popping in the exhaust. You need to fine out why, You could have the beginning of burnt exhaust valves, but this would happen all the time. I would look at the ignition first, new cap and rotor. Roadtest, then look at the timing charts. Rick L.

[BAD ASP]

Originally Posted by RICK LAKE

BAD ASP Which box are you running? The old Speed pro, the Old F.A.S.T. box. There is a problem with them when running Large injectors bigger than72 lbs with low ohms. The drivers start to break down from the amperage loads, or duty cycles if you like. You could have the 4 injectors dropping out. Need the 6 digit number from the box for what you are running. 122131? You might need to go to a XFI box. I have had a couple of problem with the BOX. The new box has traction control built in. With the power you are maken, this might be a help. If you are on wide band O2, NO LEADED GAS. Is your are tuned with the Alpha N or the other way? The only fuel problem I could see is if the regulator is not upping the pressure when boost comes on. What is the ratio of boost to pressure on your regulator? 1/2 psi, 1/3, 1/5, 1/7? You should also have an LM-1 sensor on this motor to compare O2 readings. EGT is also not a bad extra. What ignition system are you running? You said the motor is popping in the exhaust. You need to fine out why, You could have the beginning of burnt exhaust valves, but this would happen all the time. I would look at the ignition first, new cap and rotor. Roadtest, then look at the timing charts. Rick L.

Good stuff Rick, I'll be working on this over the weekend so I'll post soon.

Thanks to all for the help so far!

[fkemmerer]

Originally Posted by BAD ASP

I have a 408w with a large turbo. The engine is FI using MSD ignition and coil. The distributor is a stock Ford and I'm using a Fast sequential bank to bank ems. The injectors are 83 lb.The problem is only between 2000 and 3000 rpm. The engine misses and hesitates but you can push through it. The problem is that the rpm range is right at cruise in traffic.When cruising the engine is breaking up and popping a little. It's much more noticeable to me but I had a techie riding with me checking my ems with the laptop and he says all is good. I've changed the plugs and they showed a little rich but not bad. The A/F is right at 13.5. My gut says its ignition because the fuel pressure stays at 60 lbs and I can hear the pump.... it doesn't break up at all. Could it be an injector not spraying at the rpm or is that in the ems.... This condition is somewhat intermittent but I'd call it 80%. It also doesn't matter cold or hot.
Any thoughts will be appreciated.

This is problem is likely a driveability issue with the tune in your EFI system. First, does this happen under stready acceleration through the 2000 - 3000 RPM range or when you first step on the accelerator at an RPM in this range? Is you A/F ration at 13.5 at part throttle crusie or at WOT throttle under acceleration? Are you experiencing knock or detonation when the problem happens? Is the problem the same when the engine is cold vs. hot? When the outside temperature is cold vs hot?

I'd guess that your motor is experiencing a lean condition in this RPM range, possibly in conjunction with not enough acceleration enrinchment. These sort of "driveability" issues are pretty common when an EFI system is first installed in a car and driven on the street.

Since you are using a FAST system, I'd suggest you enable data logging in your ECU and capture (RPM, MAP, TPS %, ignition advance, Target AFR, Actual AFR, Injector Pulse %, Coolant Temp, Air Temp, O2 Correction %, and Battery Voltage) for starters. Drive the car, make the problem happen and then sit someplace quite and look at what was happening with your motor when the problem occured. Was it right after you hit the throttle? Where were you in the VE and Timing tables? Did the motor go lean (indicated by position O2 correction or actual AFR below target)? What was the target AFR when the problem happened? If you had just hit the trottle and you're still at 13.7:1 than you definitely went lean, etc. Its important that you have a clear picture of what is happening before you change the tune to correct the problem. You also want to see if the problem is at one specific RPM and load point in your VE/Timing tables or if you can make it happen for a range of cells. This will also determine what you need to do to correct the problem.

The folks at FAST can also help you if you send them this sort of log information if you don't feel comfortable making the changes yourself.