Super vee bosch motronic help

[trickycoupe]

Have got my restored RT5 all together and did first start on it today with new rebuilt motor.

Motor is Bertils based, Motronic injection / ignition, flywheel crank trigger, cam driven fixed position dissy, fuel pressure at 40psi on regulator.

Starts no problem however the thing is running mega rich on start up / warm up cycle and does not lean out in any way at any temperature. (heavy black smoke, fuel pooling in intake, fouling plugs in seconds)

Have used the mixture dash pot in every position but it seems to make no significant difference to mixtures.

Does anyone have any experience with the Motronic control unit and can offer any input, details or setup info / specs, etc.

The only info I have is to start it on full rich (position 10) and lean out to position 6 on the dash pot when warmed up / ready to race.

My alternative is to replace with a current programable ECU but prefer to keep it original if I can.

Suggestions are welcomed.

[bobmic]

I don't know anything about Motronic but I would start with measuring the pot. If it's a three lead pot you should be able to test it with an ohm meter (VOM set on ohms). Disconnect it from the ECU and set the knob in the middle position. The resistance should be higher between two of the wires, those are the ends of the resistor. The resistance should be half of that value (if the knob in in the middle) between the other wire and either of the first two wires, that wire is the wiper. You can test it for dead spots by moving the pot through the range while reading the resistance from the wiper and each end wires. It should change smoothly without dropouts. Report back what you find and I will try to come up with a next step by then.

Good luck and put up a picture of your car!
Bob

[Skip Weld]

Are you sure the regulator is actually regulating?
I never had to switch to ten and then change to 6 after it was warm to start mine but that was many years ago.
I would also put a known good fuel pressure gauge on it to make sure.


Skip Weld RT5 in the SV series 1988, 89, 90

[trickycoupe]

Bob, Skip,
Thanks for the info.

I am going by the printed instructions given with the car originally for the cold start up procedure :- ie start on setting 10 then down to 6. Nothing has changed in terms of wiring connections during the restoration so it should just run.

The cable from the dash pot adjuster from memory is 6 or 7 pin, multi core cable. Will need to isolate what pins are what. Would be great to have a pinout diagram for the complete Motronic unit .....

A new Aeromotive adjustable pressure regulator is fitted and adjusted to 40PSI. On prime, the gauge comes up to 40 and stays until pump off. Same while running. Originally it had what looks like an OEM type non adjustable regulator (They usually run around 39PSI)

Photo attached of the car prior to building an exhaust. The ex 1985 Jeff Andretti car (RT5-535)

[bobmic]

Very nice car! I have been trying to find info on the ECU. Do you know what model number it is, any more info on the box?

Fuel pressure was a good call Skip and the easiest thing to check!

If the fuel pressure is correct then the pulse width has to be too wide. That means something is driving the ECU to the wrong area in the fuel map which could be the relationship of the TPS to the butterfly's. There should be a setup voltage at a specific throttle opening. It could also be a temp sensor that is shorted or open. If the dash knob has more than three wires it is probably a switch and not a pot which makes more sense anyway. Does it have click positions or move smoothly? Check all connections to/from sensors for a wire that might have been bent or pushed back in the connector. What sensors does it use? I see the TPS and assume it has a water temp, any others? Does it clean up at higher RPM?

Bob

[trickycoupe]

Thanks Bob,

My bad, the mixture is a 10 position switch not dash pot. Will have a poke around and bell out the pins on the weekend to see what is what.

Will get a photo of the Motronic sticker / Model on the unit later and post it up.

The TPS, Air temp and water temp are all installed (original parts matched to the car)

My thoughts were with TPS for mucking up the mixture as that is the load source. The TPS is a non contact type so will have a play with that and find / set up for low and high resistance values at closed and wide open. I did not alter any linkages on it for the reason of expecting a change to load values.

As an aside, I am gathering all the bits for an ECU change for a worst case scenario. (at least it will be programmable into the future)

[bobmic]

My RT-5 has Lucas mechanical and I may try to run run it that way for a while. I did get a Redline ECU with the plan to change to electronic at some point. There are several RT-5's around here using the Redline setup. My project has been stalled for several years but I'm hopeful that I will revive it when I retire. That was supposed to happen at the end of this year but is now postponed until sometime next year.

[bobmic]

I found this information on a motronic of the same era although not the racing ECU it's probably not far off.

Correction factors are then applied for starting, idle, deceleration and part and full-load operation. The main correction factor is engine temperature (CTS). Minor correction to timing and AFR are made with reference to the ATS and TPS signals.
The basic AFR is also stored in a two dimensional map and the engine load and speed signals determines the basic injection pulse value. Motronic calculates the AFR from the AFS signal and the speed of the engine (CAS).
The AFR and the pulse duration are then corrected on reference to ATS, CTS, battery voltage and position of the TPS. Other controlling factors are determined by operating conditions such as cold start and warm-up, idle condition, acceleration and deceleration.

I don't think yours uses an AFS so probably relies more on the TPS and RPM to set the pulse width. I thought it was interesting that it says the CTS is the main correction factor.

CTS
The CTS is immersed in the coolant system and contains a variable resistance that operates on the NTC principle. When the
engine is cold, the resistance is quite high. Once the engine is started and begins to warm-up, the coolant becomes hotter and this causes a change in the CTS resistance. As the CTS becomes hotter, the resistance of the CTS reduces (NTC principle) and this returns a variable voltage signal to the ECU based upon the coolant temperature.
The open circuit supply to the sensor is at a 5.0 volt reference level and this voltage reduces to a value that depends upon the
resistance of the CTS resistance. Normal operating temperature is usually from 80° to 100° C. The ECU uses the CTS signal as a main correction factor when calculating ignition timing and injection duration.

TPS
A TPS is provided to inform the ECU of idle position, deceleration, rate of acceleration and full-load (WOT) conditions. The TPS is a potentiometer with three wires. A 5 volt reference voltage is supplied to a resistance track with the other end connected to earth. The third wire is connected to an arm which wipes along the resistance track and so varies the resistance and voltage of the signal returned to the ECU.
From the voltage returned, the ECU is able to calculate idle position (approximately 0.6 volts), full-load (approximately 4.5 volts) and also how quickly the throttle is opened. During full-load operation, the ECU provides additional enrichment. During closed throttle operation above a certain rpm (deceleration), the ECU will cut-off fuel injection. Injection will be reintroduced once the rpm returns to idle or the throttle is opened.

[Dee]

WOW, what a nice car, I have Rodger Penske Jr / Davy Jones RT 5 (287) and for the past 12 years I've used the Redline ECU it works great
Best of Luck,
Dee
Rt 5
Swift 016

[E1pix]

Car looks fabulous!

Is this the ex-Jeff Andretti car mentioned in a photo-seeking thread early this year?

[trickycoupe]

Car looks fabulous!

Is this the ex-Jeff Andretti car mentioned in a photo-seeking thread early this year?

Sure is. - A couple of very subtle differences to the livery though.

[E1pix]

Did my photo referral to Tom help at all?

I'm careful to only refer people making others' lives easier, and have been wondering.


The car is truly beautiful, really happy to see it!

It's also heartwarming to see a Bertils motor, he was the engine guy for a lifetime friend who won the 1975 S/V pro title here in the States.


(aside... if you indeed run this car in Australian Monoposto, please say Hello to my (non-blood) brother James Lambert! He runs a powder-blue, '66 Elfin in Monoposto)

[trickycoupe]

Thankyou Yes, quite helpful.

Ended up getting a couple of photos from Tom which worked well for a reference base.

As an aside, one of the local FF guru's here in Perth was a mechanic on this car when run by Jeff in 85. small world.

[E1pix]

If your FF friend was helping Jeff in FF at the ‘84 SCCA Runoffs, we would have met.

I did some hand lettering on that car, thanking the crew and “Mom & Dad.”

[trickycoupe]

My RT-5 has Lucas mechanical and I may try to run run it that way for a while. I did get a Redline ECU with the plan to change to electronic at some point. There are several RT-5's around here using the Redline setup. My project has been stalled for several years but I'm hopeful that I will revive it when I retire. That was supposed to happen at the end of this year but is now postponed until sometime next year.

Hey Bob,
Thanks for your notes. They certainly reinforce my existing knowledge of the ecu and sensor functions.

I spent some time on the WE looking over the Motronic trying different things and decided to bite the bullet and install a basic Haltech Elite550 ECU. Very reputable company and product, Aussie designed, Sold and Supported world wide and importantly Cost effective.

This is at least readily programable from any laptop and will easily run the basic batch injection, single coil and timing these cars use. As a bonus it is about a 1/4 of the size, weight and cable of the existing Motronic unit.

[bobmic]

[QUOTE=trickycoupe;613660]Hey Bob,
decided to bite the bullet and install a basic Haltech Elite550 ECU. [QUOTE]

Probably much easier to maintain and program. I hope you don't find a bad sensor when you swap it out that would have fixed the Motronic. I wouldn't be surprised if you can sell the Motronic for near the cost of the Haltech. Seems very reasonably priced!

Bob

[apex944]

Curious as to what injector specs that engine is using?

[trickycoupe]

Curious as to what injector specs that engine is using?

Injectors are just the usual bosch green top (440cc) used on most of the SV cars with EFI.

The car is all up and running very sweetly (using an ignition and fuel map from my other RT5) It's booked in for proper tuning in a couple of weeks.

After that I can start shake down / bedding in process when the circuit re opens for the year.

[apex944]

Thank you. Could anyone point me to any web resources where I may be able to find out more technical detail about these engines? I'm interested in the chronology of the water cooled SV engine's development over the years. The milestones that were reached, which engine builders/shops reached them and of course any documentation. A Bertils manual for the later EFI engines would be great. Is this info out there?

Thanks