MyE28.com

M3fan4eva wrote:Yeah, for a temporary solution, I fabricated a tiny rod with a 1/16" hole drilled in it. That turns out to be a 1.5mm diameter.

I don't know what the BEGI restrictor is either, but if it's smaller than that, I should be getting alot more power once the real restrictor comes in because I'm running a little bit rich on initial boost (up to 70psi fuel pressure)

I'd go smaller than that. Try sucking on it. Does it flow much less than a standard peice of vacuum line? If you cant tell the difference, go a little smaller.

Another entry in the saga.

I increased pressure at atmospheric to 54 psi. The problem remains. No enrichment below 4000 rpm. Then Wham. 100% enrichment.

I reduced atmospheric to 46 psi. Same exact problem just not quite as rich once it does kick in. Say, 10.6 instead of 10.1.

When I had backed it all the way out it acted the same except for AFR's were in the low 11's.

At this point I believe the FMU is suspect.

Have you disassembled it and inspected the piston? It might be sticking. The instructions I got with my rebuild kit specifically mentioned that it can gall if not lubricated with moly based grease. You can take it apart installed on the car. Just remove the center screw, the four allen bolts through the top and un-stack the spring and washer and main diaphragm. The main diaphragm bolts into the piston IIRC, so you may need to remove the bolt that goes down through the top. Check to see if the piston below the diaphragm is lubricated and moving smoothly.

X2. I saw a rebuild kit on the BEGI website for about $30.

Albeit, you shouldn't have to pay for it unless you dropped it or whatever, but it is there. check for play, or lack thereof and you should be okay. After reading this whole thread, I think that it's your FMU as well. Good luck!

On the contrary, I think thier continuing support and reasonable pricing for the rebuild kit is great. Nothing lasts forever, and especially when you buy one used its a good idea just to make sure its in tip top shape. They ship quickly too. In my case I didnt even need the kit. The lower shim had merely been placed too far off center, allowing a slight external fuel seep. But I replaced the lower and main diaphragms, shims and everything anyway. Good stuff..

Mine is new. I spoke with Corky earlier and he said if I continued to have problems he would send me a new piston free. He also offered to go through mine if I sent it to him.

Dan,
It seems that either I threw my restrictor out by accident bc it was so small, or I just never received one either. I just called BEGI and told them the situation with my home made restrictor and how it has a 1/16" diameter hole, which is equivalent to around .0625".You said yours was 1mm which equals about .0393 inches.

The guy at BEGI said that the actual restrictors are about 20 thousanths inner diameter, which is quantitatively .020 inches. I think that both of us were off by quite a bit if you compare the numbers

They are $3.00 and shipping is probably the same. I would order one if I were you.

Well I finally got my fuel pressure gauge in the right place. Fuel pressure rises with boost pressure in a linear fashion just as it should. At 5 lbs I am seeing 58-59 psi and at 7lbs 64-65 psi. Non boost pressure is 38-42 depending on vacuum. Pressure with the signal line removed is 48 psi.

Well at least I know the FMU is good.

I am still having the weird AFR issue with stoich below 4100 rpm and then 10's to 11's above that.

Perhaps my car isn't going into open loop @ WOT below 4100 rpm and the ECU is compensating when it shouldn't be. Then it goes ultra rich when it does go into open loop. I really don't know. Just hazarding a guess.

Runs without the O2 connected showed better AFR's overall but still pig rich above 4100.

I must admit, I am lost on this one. Too much time chasing ghosts. I am needing to take a break from it and get a fresh perspective. I might just drive it in it's current "lame duck" configuration until I get my standalone. At least it's a safe tune.

My other thought was to put the stock injectors back in. I am not wanting to do this but the car is all over the 9.8-10.3 AFR range up top. Shitty mileage and low power are not the goals I have in mind.

I even tried removing the check valve on the FMU vent line completely thinking it might be a restriction. No effect.

I am tired of risking my license on a pull, pulling over to make an adjustment, doing another pull, making another adjustment and not having any discernible changes regardless. Frustrating doesn't quite cut it. If anything made a difference I probably would have some enthusiasm in finding the solution.

Sometimes learning new stuff is no fun

You should try a new O2 sensor and O2 relay to start with when you decide to work on it again...

Got a brand new O2 in there now. O2 relay? do tell.

Greg,

Test your TPS. You obviously have a system failure unrelated to the turbo itself. It has just reared it's ugly head with the addition.

Todd

Greg,

Although you've confirmed the FMU is raising the fuel pressure, it appears you might be getting too much fuel pressure. This is the only adjustment you have other than the AFM which gives you some control over injector pulse width.

Does the WBO2 you're using have a logging capability? Something to consider looking at, tap the AFM signal into the ECU and monitor the voltage to the ECU when you are off boost and when you start to make boost. If you see the AFM voltage swing to quickly towards 5 volts, the injector pulse width could be increasing more quickly than needed. This would mean tightening the spring tension which obviously would impact your idle A/F ratio. To reset the idle A/F ratio would require moving the wiper arm on the shaft to re-establish the idle A/F ratio at stoich.

FWIW: I know of a place you could probably do your pulls and not be bothered by LEs.

Rich

Todd, I went through the TPS a month ago. It all checked out then. I guess it could have broken since then so I'll check it again.

What about the kickdown switch under the accelerator? It's left over from the automatic. I wonder if it's keeping the throttle from opening all the way. Acting as a throttle stop. Hmmm.

When I open it by hand under the hood the switch works. But maybe it's not going all the way when using the accelerator. I'll have to test this tomorrow.

It still doesn't explain why my AFR's are so fat up top though. I suppose lowering the rate of rise on the FMU would help. Maybe I'll drill out the bleeder hole and replace the valve with a much larger one. Just a thought.

Also Sweeney asked earlier whether I had the 1/8" or 1/4" fuel ports on my FMU. Which should I have?

GregATL wrote: Also Sweeney asked earlier whether I had the 1/8" or 1/4" fuel ports on my FMU. Which should I have?

Doesn't matter. Not sure why he asked.

Greg , could this be related to the problem you had before the Turbo installation ? Just a thougt , I know its frustrating . Maybe you have another wiring issue.

T_C_D wrote:

GregATL wrote: Also Sweeney asked earlier whether I had the 1/8" or 1/4" fuel ports on my FMU. Which should I have?

Doesn't matter. Not sure why he asked.

Gathering all info.

Defective airflo meter? Chip maybe?

Well I found a problem most likely the problem. As Todd suggested TPS. It works fine and all the contacts are good. Except that it won't turn far enough to engage the WOT switch when on the car. If I take it off the car and do it by hand it works no problem. I have opened it up and checked the little spring arm and it can't really be adjusted in a way that will make it contact any earlier without compromising it's reliability.

I have ordered a new switch and should be able to pick it up this morning. If it still doesn't work then I will start fooling with the throttle body linkage and or cables to try to get more sweep out of it.

I hope this solves my issue and I can get this car tuned today.

That arm can be adjusted. I'm pretty sure you just bend it. Todd and Sweeney adjusted theirs at one point so that it tripped the WOT switch at about 3/4 throttle instead of just WOT so they could get the O2 sensor to stop messing with the AFRs.

You've got a spare in the mail, what can futzing with the current one hurt?

Jeremy

GregATL wrote:Well I found a problem most likely the problem. As Todd suggested TPS. It works fine and all the contacts are good. Except that it won't turn far enough to engage the WOT switch when on the car.

Why would this cause your problem? From what I know, the WOT switch takes the ECU open loop mode and the ECU goes to internal fuel maps. If it does not do this, the ECU will stay closed loop and should not be going rich.

My problem is that I am at stoich until 4100 rpm. Then full on rich. I am making 7 lbs of boost by 3000 rpm. I know I should be seeing enrichment during this time. It is just very difficult to tune the enrichment curve when you cannot see it in real time.

I found the solder joints within the TPS cracked on a few of them also... might want to check them.
At one time or another I had wired an adjustable pressure switch into the WOT circuit to switch relative to boost without actually being WOT.

Duke M535ti wrote:Why would this cause your problem? From what I know, the WOT switch takes the ECU open loop mode and the ECU goes to internal fuel maps. If it does not do this, the ECU will stay closed loop and should not be going rich.

Motronic will only correct so much. Eventually, when it just becomes too much for it to correct for based on O2 feedback, it ignores the O2 input. When it goes to the internal maps, Greg goes pig rich. I'm guessing when he gets the TPS working correctly he'll find that he's rich at WOT all time

Greg, you could also tune WOT with the O2 completely disconnected until you get the TPS situation resolved. This will allow you to continue tuning while you wait for your new part.

Jeremy

EDIT: said lean when I meant pig rich, oops

Jeremy, I have thought about that and will do so if I didn't just fix the problem.

I started looking at how the cam inside the switch and thinking maybe I could just reorient it in relation to the follower on the WOT switch. I decide to put it on the car with the cover off and see exactly why it wasn't contacting.

It was contacting. Before when I had it off the car it would pass a signal when it made contact. So without removing it from the car I connected the leads on my multimeter to the pins on the TPS plug. Then with the cover still off I opened the throttle by hand. When the switch contacted, approximately 85-90% through the range of the throttle body, the signal went through every time.

I decided that I would drive the car right then since it was working. Good decision. The AFR's did exactly what they were supposed to do. Went down in a linear fashion as boost went up. They still went down further than I want but at least I have gotten it off of stoich as boost builds.

Now I feel confident that I can get a satisfactory state of tune on the car with a little effort.

So what did I figure out. The TPS won't go into WOT on the car with the cover in place. I had to order a new one. Seems there aren't any in Houston that I can pick up.

Also, the car is much stronger through the midrange now. No more surging( hesitation) as the rpm's go up. Probably due to being lean. (14.7:1 @ 7lbs= lean)

I am finally getting excited to tune it again.

GregATL wrote: I am finally getting excited to tune it again.

GREAT! I know just how you feel. I am still slowly getting over spontaneous HG failure fear. If my coolant light comes on again and the car temp sky-rockets, I will just drive it off a cliff. Um..............no cliffs around here, lucky me.

Good to hear you're moving forward again.

As far as the surging goes, that'll be present under boost at part throttle to some degree. The FMU will be fighting the O2 sensor for control, and the mixture will oscillate between stoich and where it wants to be, hence the surging.

The way around this is to build a device like Sweeney mentioned. It's a pressure switch in line with the O2 sensor signal lead to the ECU. When it sees positive pressure, the switch opens and the ECU has no O2 feedback, forcing it to go to the internal maps and proper fuel AFRs.

Never bothered with it myself, but it's an option.

Jeremy

Good find Greg Now get her dialed in and give me a ride.

Glad you found that Greg. I may have a spare TPS switch in the garage and you are welcome to borrow the one off my 533 if you want until yours comes in. Did you order one from the E34 automatic with the linear resistance function for your future stand alone ECU?

Edit: I do have a spare TSP, but I haven't metered it yet. Let me know if you want it. Nine 3 six - 32 one- 5 two 8 four (till 9 PM, I have to be up at five) or email or PM.

Greg I may have a used one you have till yours come in let me know.

Jimmie

Jeremy, as strange as my AFR situation was the car drove really well under moderate throttle situations. Not really any surging that was obtrusive.

Under full throttle and boost it surged quite a bit. My opinion on that is that it was a lean surge. Now under boost it doesn't noticably surge. In fact it has a really nice big torque feeling. Much stronger than before.

And thanks for the offers on the TPS. I have managed to get mine working for now. It could quit again tomorrow. I have one on its' way right now so I'll just live with it a few days if it does.

Car feels really fun right now. I am eager to turn up the boost.