Turbo M20: MS2PNP and Fuel Pump Relay Problem

[Antpaolo]

Hi R3V,

Long time reader, but first real post here.

I am experiencing a problem with my newly turbo'd m20b25 setup using MSPNP2 standalone. Before I get into the problem the title alludes to, I will just give a quick background of the setup itself and provide relevant info:

-The E30 in question is a U.S. spec 1991 325i.
-Originally automatic, swapped professionally to g260. The ZH4HP22 was mechanically controlled so I do not believe any crucial wiring was manipulated during the swap.
-Completely stock late model M20B25.
-New M20 MSPNP2 ECU purchased from DIYautotune.com.
-New Holset HE300 turbo, cast iron t3 manifold.
-Siemens Deka 630cc injectors.
-New VNE M50 variable TPS.
-Single Wideband O2 and controller, Bosch sensor.
-Stock fuel pump and FPR for now.

-Prior to installing the turbo system, this car has been my daily for nearly 6 years and has always been reliable and free from engine-related problems. The M20 has had all of its sensors replaced over my ownership and much more.

-Everything has been programmed appropriately in TunerStudio (correct base map, timing set, correct req_fuel for the injectors, wideband calibrated and linked, sensors and tables calibrated, etc.) So I assume the car would at least start on these inputs.

Photo of the engine bay for reference of what setup we are dealing with:



So, here's what's going on. From when I first installed the MS two weeks ago until this evening, I have been trying to start the car on the MegaSquirt system. Each time I would attempt to start the car, it would either not start at all or start briefly and then die rapidly (after approx. 10 sec). The MS was getting a crank signal, TPS signal, and the rest of the sensors seem to be communicating with the ECU. The MS has 12.00V and it does not drop drastically while cranking. So, naturally, I assumed the engine was not receiving fuel and I started messing with ASE, WUE, and Cranking pulse %. This did not help. Keep in mind I am a complete tuning novice. I pulled the plugs and noted they were wet with fuel. I also later checked spark and it was fine. So I have spark, fuel, and the timing is correct or at least in the ballpark (this should at least start the car). To rule out a bad CPS or any problem with the motor itself (maybe I damaged something while installing the turbo system) unlikely but who knows, I put the stock injectors back in and started the car on the stock DME. It fired right up. So no problems with the motor or associated wiring. Now I turned my attention to the MS. It must be in the tune I thought initially, so I kept manipulating inputs in Tuner Studio and researching over the past weeks but was ultimately stumped. The car would just crank and not start. I never suspected the fuel pump relay and associated system to be an issue, as the car works on the stock DME, so it must be fine. Also, with both the stock DME and the MS I hear the relay click. This evening, though, I had a thought: maybe the fuel pump is not staying on when the car actually catches and starts. This is why the car would catch and die after ~10 seconds regardless of how much I increased fuel. Maybe the MS is not telling the fuel pump to stay running. To test my theory, this evening I jumped the fuel pump relay, started the car, and it fired right up. I was able to do some idle tuning as well. I was rather confused. Why did the stock DME work to start the car with the relay and MS not? Does MS modulate the relay and associated system in a different manner? I don't think so, right?

So, R3V, my central questions are: what may be causing the MS to not keep the fuel pump running? Could the fuel pump relay be nonfunctional or "off" slightly to a point where the MS is unhappy? Is it a problem with the MS ECU itself? Maybe my car's DME harness?

Your help would be greatly appreciated. Let me know if anyone has experienced a similar problem or if you would like data logs, photos of my TunerStudio settings, or any clarification on what I just described.

Thanks R3V,

-Anthony

[varg]

Go into output test mode inj/spk in tunerstudio and turn the fuel pump on, does it respond and stay on? If it does, MS doesn't think the engine is turning, if it doesn't there's some other issue. Maybe go back to the out-of-box base tune and see if it works with that loaded. Assuming you set the req fuel up correctly and didn't mess with any other settings it should start right up, do yourself a favor and verify spark advance against the timing mark with fixed angle enabled before you start tuning, I seem to recall the PNP base tunes having the wrong offset angle. I've haven't messed with an M20 MSPNP2 in years but I would assume it is indeed plug and play with zero wiring modifications unlike my homebuilt which required messing with the main relay wiring. As an aside, you will max out the stock pump with the flow that turbo can put out in no time at all, you probably won't max out the fuel rail and regulator though.

[Antpaolo]

Go into output test mode inj/spk in tunerstudio and turn the fuel pump on, does it respond and stay on? If it does, MS doesn't think the engine is turning, if it doesn't there's some other issue. Maybe go back to the out-of-box base tune and see if it works with that loaded. Assuming you set the req fuel up correctly and didn't mess with any other settings it should start right up, do yourself a favor and verify spark advance against the timing mark with fixed angle enabled before you start tuning, I seem to recall the PNP base tunes having the wrong offset angle. I've haven't messed with an M20 MSPNP2 in years but I would assume it is indeed plug and play with zero wiring modifications unlike my homebuilt which required messing with the main relay wiring. As an aside, you will max out the stock pump with the flow that turbo can put out in no time at all, you probably won't max out the fuel rail and regulator though.

Thanks for the response varg, it's much appreciated.

So I went to output test mode inj/spk, and clicked fuel pump on, and I heard the click of a relay but no fuel pump. So it appears the MS is not turning the fuel pump on. I did what you said and went to back the m20 base tune that was sent with my ECU via a flash drive and the same thing happened, crank but no start. I checked the fuel pump with the base tune as well with inj.spk test mode and nothing. So ultimately, it seems the MS is not turning the pump on as I thought. It is important to note that I can start and drive the car if I jump the fuel pump relay pins to keep the fuel pump running perpetually. As soon as I place the relay back, nothing. Just cranks but doesn't start. At least we have narrowed down the problem. And yes my req_fuel is correct for my target afr or 14.7, 630cc injectors, and displacement. Thanks for the heads up about the timing. I will make sure to verify. I also checked and the tooth#1 angle in TS and it was pre-set to 97, where that figure should be 84 I believe. And yes, this unit is a proper PNP with no wiring required on my part.

Thanks for letting me know about the fuel pump, I wasn't quite sure how much power it can support. Some have said up to 300 whp on the stock pump but that seems high. In your experience, do you think this stock late model in-tank unit can support 5-7 PSI for now? I'm not comfortable running more until my ARP head studs arrive, they have been back-ordered for a while now, unfortunately. Also, Is there a specific pump that works well and is reliable for an m20 turbo setup with the goal of producing ~320 whp on 93-octane gasoline? I was going to go with a Bosch 040 and rig it in-tank. Sorry for all the questions, I would like to take advantage of your knowledge, as you have done it before.

[varg]

It's odd that there's a click but the fuel pump relay doesn't turn on. According to the ETM, Motronic receives +12V on pin 27 when the ignition is turned to the run and start positions, at which point it it grounds pin 36 which closes the main relay. When it primes or senses that the engine is cranking, Motronic grounds pin 3 to close the fuel pump relay. At some point it grounds pin 23 to close the oxygen sensor relay. There's a constant +12V on pin 18. Which relay is closes when you enable test mode?

I don't know how much the stock fuel pump will support, you can generally tell that it's tapping out when the fuel pressure drops under boost or if you can't see that the VE values climb at a higher rate than normal as you increase boost. I generally use Deatschwerk pumps, which I purchase directly from them. My car has a DW300. I haven't used the walbro 255s because there are so many fakes and no warranty, and am not familiar with the Bosch 040 in this application.

[Antpaolo]

It's odd that there's a click but the fuel pump relay doesn't turn on. According to the ETM, Motronic receives +12V on pin 27 when the ignition is turned to the run and start positions, at which point it it grounds pin 36 which closes the main relay. When it primes or senses that the engine is cranking, Motronic grounds pin 3 to close the fuel pump relay. At some point it grounds pin 23 to close the oxygen sensor relay. There's a constant +12V on pin 18. Which relay is closes when you enable test mode?

I don't know how much the stock fuel pump will support, you can generally tell that it's tapping out when the fuel pressure drops under boost or if you can't see that the VE values climb at a higher rate than normal as you increase boost. I generally use Deatschwerk pumps, which I purchase directly from them. My car has a DW300. I haven't used the walbro 255s because there are so many fakes and no warranty, and am not familiar with the Bosch 040 in this application.

Thanks again varg. I haven't had much time to tinker with the e30 until recently.

The fuel pump relay is the one closing when I enable test mode. I've ordered a new relay for good measure and I'm awaiting delivery. If a new relay resolves this I will update. For now, I've wired a toggle into the cabin to manually jump the relay so I can at least drive the car as a daily. It pulls hard and everything is fine so far besides this fuel pump relay issue.

I see, thanks for the fuel pump advice. I'm going to try the DW 300 kit, good price and I like how it has a new hose and screen. I assume it's been reliable for you? I will update the thread if I fix the problem or if I find anything else that may be contributing to this.

Also, since my ARP preorder shipment date has been pushed back once more, I was going to get Raceware studs instead. Do you have any experience with or anecdotes of people running these with success on any boosted motor? I've searched R3V and the e30Tech archive but there are no distinct anecdotes with these, people either use ARPs or MB. I can't find any info on the specifics of their alloy either. I'm strongly against using a generic 12.9 as well. I would like to increase the boost after the new fuel pump and get this on a dyno soon.