408 magnum tune, going lean

J

johnnmo

Active Member
I need help.
I have a new 408 mopar magnum that we cannot get the tune right.
Edelbrock heads 10.1 compression
Cam is a fast ramp .220 duration factory rollers
Edelbrock intake ( this replaces the factory barrel, so I can use the complete factory injection)
Shorty headers into stock exhaust.
30 lb injectors--Accell

Problem.
We have tried 6 tunes so far.
It goes very lean off idle , and into surge. 14.5 to 15 to 1 at idle and cruise but as soon as the converter is starting to get a load it leans out to 18-19 to one.
Cam sync set to zero and to +7 No change
Every sensor has been replaced with no changes in performance.
This includes TPS , MAP, IAC, Cam signal plate.

It is currently returned to stock--injectors and programming.
It still has the lean off ile but not as pronounced.
(it is not as snappy either!)

We have added as much as 30% more fuel and it still does it. ( on top of the injectors)
It will go rich to 11.5 at full throttle 3k to 6k rpm and makes great power.

This can't be this tough!!
I'm missing something, help!

Today I plan to swap out the TB, I have two, both stock.

Plugs are staying white.
Gas is 91 octane.
John
 
My experience with Dodge/Mopar is that when all else fails--read the install manuals first when adding aftermarket parts--then replace the ECM with one that is programable.
 
We are looking for 400-425 HP

It is a factory ECM.

Yesterday, after thinking thru everything that has been changed, I realized that the TB had not been changed.
I have a spare so I replaced it.
Same part number, both from 5.9's
They look almost identical, measure the same. The gasket was compressed fully all the way around it.

Started right up and went for a drive.
So far it looks like the problem is gone. I will drive it today.

Passages are open so the Map has signal shaft is not 'loose'.
So I thought possibly the IAC was not sealing. Computer could of been trying to correct it.
But then I realized the tuning is not going into closed loop.

BTW, it is still 15 to 1 at idle and varies from 15 to 16.5 driving it, until 50% or more load and throttle, where it is going to 12. to 1
Sloppy idle, to rough for what it is. I'd let that go if the cam was 245 degrees.

Just a little history on this truck.
Recently purchased for this project.
170,000 miles.
2001 Ram 2500
It was showing /getting 15-16 mpg driving it home but only ran 70 mph floored.
Upon, opening up the old engine, I found the distributor rotated one position CW with the plug wires moved to compensate. ( someone thought they were advancing the timing, when all they did was retard the injector timing.)
 
johnnmo said:
We are looking for 400-425 HP

It is a factory ECM.

Yesterday, after thinking thru everything that has been changed, I realized that the TB had not been changed.
I have a spare so I replaced it.
Same part number, both from 5.9's
They look almost identical, measure the same. The gasket was compressed fully all the way around it.

Started right up and went for a drive.
So far it looks like the problem is gone. I will drive it today.

Passages are open so the Map has signal shaft is not 'loose'.
So I thought possibly the IAC was not sealing. Computer could of been trying to correct it.
But then I realized the tuning is not going into closed loop.

BTW, it is still 15 to 1 at idle and varies from 15 to 16.5 driving it, until 50% or more load and throttle, where it is going to 12. to 1
Sloppy idle, to rough for what it is. I'd let that go if the cam was 245 degrees.

Just a little history on this truck.
Recently purchased for this project.
170,000 miles.
2001 Ram 2500
It was showing /getting 15-16 mpg driving it home but only ran 70 mph floored.
Upon, opening up the old engine, I found the distributor rotated one position CW with the plug wires moved to compensate. ( someone thought they were advancing the timing, when all they did was retard the injector timing.)
Click to expand...
See if Mopar Performance offers a different ECM.
 
johnnmo said:
Thunderbolt, who sells other ECM,s ?
Click to expand...
I thought maybe you used an aftermarket ECM like Holley, Halltech, AEM.

I have a RAM 1500 2003 5.9 V8 and cant find a way to tune the ECM like the Chevy LS guys, i have read about Hemifever tunes for the Magnum V8, but nothing d.i.y.
I have a Superchips programmer, but its limited, no diy tuning options.
 
No luck trying to find a mopar performance computer.
I suspect a wiring break causing the issues with the TB change.
18 year old harness?
I will again try the stock computer with stock injectors, hopefully today.

On the computer topic, this truck is a factory califonia emissions truck.
Maybe it cannot yet be configured to accept a tuner?
 
johnnmo said:
No luck trying to find a mopar performance computer.
I suspect a wiring break causing the issues with the TB change.
18 year old harness?
I will again try the stock computer with stock injectors, hopefully today.

On the computer topic, this truck is a factory califonia emissions truck.
Maybe it cannot yet be configured to accept a tuner?
Click to expand...
I would try contacting a guy on a Mopar Performance Board. They call them Boards instead of Forums the Dodge guys.
A good one with lots of Hotrod info is the 1969 Charger Registry.
My Best bud Bob is a Mopar Guy. He is on there.
He has a 1970 Charger SE fully Restored but no engine yet. Getting built in 2019 that 500 ci Wedge engine.
 
Try these folks as they were the only ones able to help me out when no one else could/would. Ask them if they can make a programmable ECM for your VIN numbered vehicle with your setup. They have Technicians there that may be able to help.

Flagship One Engine Computer in N.Y.
 
Flagship 1 was no help. All she offered was a replacement ECM.
We already put a replacement ECM in it.
We tried a new tune and the problem came back. 1500, light throttle and load, it goes lean---18.5 to 1 and surges.
So right now I have stock injectors--24lb-- in it with stock tune and it is driveable. Drives nice but not as snappy as the tunes we tried.

With all the things I have tried and checked, the original ECM had the wrong VIN in it. This may be why the dash lights were on.
The ECM in it now is the correct VIN. I doubt this has anything to do with the problem, but it shows I bought someone elses problems when I bought it!

I maybe forced to put a carb on it, with a standard distributor. I can tune that.
 
you really need to try to put the 30 lb injectors in the car.

you original stated you had
"30 lb injectors--Accell"

then you stated you had,
"So right now I have stock injectors--24lb-- in it with stock tune and it is driveable.|
 
johnnmo said:
Flagship 1 was no help. All she offered was a replacement ECM.
We already put a replacement ECM in it.
We tried a new tune and the problem came back. 1500, light throttle and load, it goes lean---18.5 to 1 and surges.
So right now I have stock injectors--24lb-- in it with stock tune and it is driveable. Drives nice but not as snappy as the tunes we tried.

With all the things I have tried and checked, the original ECM had the wrong VIN in it. This may be why the dash lights were on.
The ECM in it now is the correct VIN. I doubt this has anything to do with the problem, but it shows I bought someone elses problems when I bought it!

I maybe forced to put a carb on it, with a standard distributor. I can tune that.
Click to expand...
You have to get into the BIN Binary files.
Set your injector size.
Set your Injector Offset Time.
Set your battery offset voltage engine running alternator charging.very important to do.
 
About ten years ago I built a similar engine in a Durango. It was stock heads and a little less cam. It ran pretty good with stock injectors and stock tune.
So I decided to try it.
It is running better that anything else tried so far.
I can put the 30 lbs injectors back in in 30 minutes.
Maniac, you are talking over my head on this. I don't have the equipment to do that!
The 30's are too rich at idle, so I tried the 24's. A/F is 13.5 now at idle and doesn't go over 15.
This is stock tune in the ECM.
 
johnnmo said:
About ten years ago I built a similar engine in a Durango. It was stock heads and a little less cam. It ran pretty good with stock injectors and stock tune.
So I decided to try it.
It is running better that anything else tried so far.
I can put the 30 lbs injectors back in in 30 minutes.
Maniac, you are talking over my head on this. I don't have the equipment to do that!
The 30's are too rich at idle, so I tried the 24's. A/F is 13.5 now at idle and doesn't go over 15.
This is stock tune in the ECM.
Click to expand...
I worked in a Chicago race shop building engines 2 times.
Also had a Mustang AWD Chassis Dyno there & HP Tuners Software & worked with a Pro EFI Tuner.
Its how it is done as I said in my last post.

Unless you can get into the ECM Software to Tune your wasting your time.
1) Put the stock cam back in.
2) Or install a carburator and old school ignition distributor & eliminate the ECM.
3) Or You purchase an aftermarket stand alone racing ECM.
4) Throw the stock ECM into the trash can.

What your up against & have to decide.
 
injector pulse duration is controlled by software , if the 30 lb were too rich at idle and swapping to the 24 lb made it leaner,
the reason was software was keeping the pulse duration similar and not using the oxygen sensor data to measure and compensate,
the at idle F/A ratio should be close to 15:1 and that ratio should get richer as the rpms and load on the engine increase.
injector size limits upper rpm f/a ratio, not at F/A idle, thats totally software and pulse duration.
 
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Get a system that is programmable and separate from the rest of the car. 2 computers , one for car and other for fuel management. Always read installation instructions first and most problems can be solved.

Everything is possible if you have enough money, but just because you can doesn't mean you should. Sometimes simple is best but not perfect or what you want.
 
Grumpy said:
injector pulse duration is controlled by software , if the 30 lb were too rich at idle and swapping to the 24 lb made it leaner,
the reason was software was keeping the pulse duration similar and not using the oxygen sensor data to measure and compensate,
the at idle F/A ratio should be close to 15:1 and that ratio should get richer as the rpms and load on the engine increase.
injector size limits upper rpm f/a ratio, not at F/A idle, thats totally software and pulse duration.
Click to expand...
It likes the stock injector Offset time Grumpy.
Often not published.
Have to get from aftermarket Injector companies the injector Offset.
 
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