Mod'd engine troubles

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WALTER

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Gents,

Hoping to tap into your collective knowledge to troubleshoot a problem my modified engine swap is running into. My mechanic, currently in the midst of tracking the problem down, has had the car on the Dyno a few times as he is tuning it and he tells me that it is "running out of power" above 3500 RPM almost like there is a rev limiter. The details of the motor are that it is an M30B35 from an 1989 735i; it has a custom ground cam, Megasquirt, 1.3 motronic, and ITBs and intake plenum from an s38 M5. Initially he thought it might be a restrictive exhaust, so we went with IE headers and custom, freer flowing exhaust, but this hasn't made a difference. He says he has it dialed in; it's running smoothly, cold start is good, etc.; however, above 3500 its running out of power. Any advice/experience is greatly appreciated.

thanks,

Walter
 
so what color are the plugs / exhaust after the run? are you leaning out ... or not getting enough air? don't you have a wide band o2 sensor on the megasquirt? it should answer the fuel / mixture issues ... unless the fuel pump can't get you enough gas.

my initial 2 cents ...
 
I will ask about the plugs/exhaust. He did install a wide band O2 sensor; pump is from an e30 which is operating ok.
 
Walter,

This may be obvious, but have you checked the ignition settings in MS? There is a high RPM cutout setting (probably in the ignition menu). There are also some retard settings - but I have not used any of those. You might also check the MS forum for this issue.

Have you checked the duty cycle of the injectors with megalog? Perhaps they are reaching their peak, undersized?

This is probably unlikely, but I have always wondered about it: Is there enough overlap of the distributor rotor end contact with the cap contacts? That is, at higher loads/rpms your advance may be getting up to the high 30's low 40's. At some level it has to cut out. Or, is this issue perhaps caused by the distributer rotor shaft not aligned correctly (I am not sure if there is any adjustment in the b35 rotor or whether is only fits on one way).

my thoughts,
 
Sven,

Thanks for the leads. I will check out the Megasquirt forum for people who have had similar issues. Unfortunately, I am in Monterey and my car is in Oceanside, so I don't have easy access to it. I will ask these questions of my mechanic tomorrow.

thanks,

Walter
 
exhaust

Timely post as I am going through the same process and results in my modded E28 5 series. At the risk of hijacking your thread a bit, can you tell me what you used for an exhaust besides the IE headers?

Any details on the cam?
 
Here is the latest from my mechanic,

"still no go as of the end of the day. Its definately a problem related to the crank sensor setup either in the stock m30b35 harness we are using or with the megasquirt. just have to figure out what exactly and where. the signal cuts off. I tried messing with the distance between the crank sensor and crank pulley and was able to get the cutting out to move up and down the rpm range a few hundred in either direction so i know its involved with that."

Again, any ideas are appreciated.

TodB,

here is a picture of the exhaust that was fabricated. My mechanic states that it is little louder than stock w/o being annoying ; ) Cam is a custom ground from Paul Burke, I forget the specs, but I'll get that info and post.
 

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Walter,

A couple other things to check. Some or all MS boards need some jumper changes made to the main board. My v3.0 board required this. I am assuming this was done because the engine works at the lower rpms. This is what I had to do:

For VR Sensor:
Jumpered TachSelect to VrIn
Jumpered VrOutInv to Tsel

There may also be a tiny potentiometer that needs some adjustment. This should all be in the manuals section of the MS site (http://www.msextra.com/doc/index.html). I do not think the distance between the sensor and wheel should be that sensitive. It may change the timing very slightly (ie, when it reads the rising or falling edge of the signal).

Grounding is also important for MS and has been known to cause problems. It is recommended that all sensors be grounded to the same place.

Dwell time. If this was too long would it might effect the spark at higher rpms.

What version are you running? MS2/extra? MS3?
 
Running out of gas at 3500 is usually the TPS WOT. Running out of spark is the green/brown wire to the main relay from the ECU.If you are running an e32 wiring harness- have your guy check the black/brown and black-blue wires to the TPS. They should be cross wired to the Black and Yellow wires at the TPS. The Brown wire at the TPS should be spliced into the Brown/Orange wire at the ECU.
Keep in mind that there are 2 black/brown wires in that harness and you need to avoid the one that goes to the cruise control.
Have your guy call call David at ecartoys... You can email me for a phone number.
 
BTW- I spent the day today at Coupekings installing a MS . Will be there tomorrow doing a autotune. Call if you have questions.
 
exhuast

Cam is a custom ground from Paul Burke, I forget the specs, but I'll get that info and post.

I have a cam from Paul as well. You're going to love it.

Good luck sorting your high RPM issue. Sounds like you are close.
 
Walter,

If you can send me the msq file or a log file I can take a look at it.

Without the msq or log file it is impossible to diagnose what you are describing.

Thanks.


Sven,

Did you get yours up and running? We have new ignition tables to try out if you need more.



David
PS You can send it to gearheadhq at gmail dot com
 
Last edited:
Not much of an update for you. My mechanic is still sorting issues; it runs smooth now but "super underpowered." He's going back under the valve cover to make sure the cam timing is correct, and checking a couple other things.

Attached are a few pics. I've deleted the big bumpers and will have to contend with those huge holes when I get it back.
 

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It has been a while since I updated this thread and a lot has happened. The shop that I was using for this engine mod was in over its head. They could not figure out how to make the ITB setup run properly. After they had the car for over a year and a lot of my my money, I had to cut my losses and hand the project over to someone I knew could get the job done. In this case it turned out to be three people who came to the rescue: Don Lawrence, David Foong, and Erik Sliskovich.

We made the determination that the previous shop had done enough damage to the engine that it was better to start with a fresh one. Don located a good engine for me and the car was sent to Coupeking's shop. I decided to drop the ITB setup in favor of the tried and true CSi manifold. Basically, it came down to money and a desire to keep the project simple. I had enough of the shop trying to get it to work. Honestly, I didn't expect much in the way of performance gains from the setup anyway, I wanted it more for the looks and the rarity. In the end, Don and David could have made it work, but I lost interest in the mod.

On top of the other failures of the previous shop, they must have caused a small engine fire because the engine compartment had fire residue. So at this point, rather than put a cherry engine into a jacked up engine bay I decided to have Erik repaint the engine bay. Erik sent out the engine to be resealed and painted and all looks beautiful now. Engine is in the car and hopefully my car will be moving under its own power soon. It's feels good having the right people working on my car.

http://www.coupeking.com/sienna-cs-engine-bay-detail-4934
 
WALTER said:
It has been a while since I updated this thread and a lot has happened. The shop that I was using for this engine mod was in over its head. They could not figure out how to make the ITB setup run properly. After they had the car for over a year and a lot of my my money, I had to cut my losses and hand the project over to someone I knew could get the job done. In this case it turned out to be three people who came to the rescue: Don Lawrence, David Foong, and Erik Sliskovich.

We made the determination that the previous shop had done enough damage to the engine that it was better to start with a fresh one. Don located a good engine for me and the car was sent to Coupeking's shop. I decided to drop the ITB setup in favor of the tried and true CSi manifold. Basically, it came down to money and a desire to keep the project simple. I had enough of the shop trying to get it to work. Honestly, I didn't expect much in the way of performance gains from the setup anyway, I wanted it more for the looks and the rarity. In the end, Don and David could have made it work, but I lost interest in the mod.

On top of the other failures of the previous shop, they must have caused a small engine fire because the engine compartment had fire residue. So at this point, rather than put a cherry engine into a jacked up engine bay I decided to have Erik repaint the engine bay. Erik sent out the engine to be resealed and painted and all looks beautiful now. Engine is in the car and hopefully my car will be moving under its own power soon. It's feels good having the right people working on my car.

http://www.coupeking.com/sienna-cs-engine-bay-detail-4934
Click to expand...

Walter, sorry to here you had so many issues sorting your car.

Someone (from second shop I believe) had briefly contacted me approx. a year ago and I told them I would offer them any assistance necessary to complete your project but I never heard from them again.

Its a shame that, as you say "the right people" weren't involved from the beginning.

Call me at your convenience, I may be able to help you move (sell) some of the pieces your not going to use.

Paul
913-728-2211
 
Paul,

Thanks for the offer, but I was able to sell the part associated with the project. No doubt, the quality of the adapter plate you fabricated contributed to the quick sale.

thanks again,

Walter
 
Update

The long journey with my '74 coupe is thankfully coming to an end. Here are a couple of shots of the CSL bumper/Alpina air dam mounted, reflectors deleted, and a shot of the new engine. Left to do are the install of the correct driveshaft and a final tune (gotta get rid of the "automatic" script on the trunk too). Special thanks to Erik Sliskovich aka Coupeking and Don Lawrence (sfdon) for rescuing my project and getting it to this point.
 

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