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Hello,

I have an e23 745i. it is chipped, TiaL 38 mm WG, Team 745 boost controller and a rising rate fuel pressure regulator. The problem I am having is that when the car hits full boost (set to 9PSI right now) the AF gauge shoots lean and the car cuts the throttle. I'm assuming it's the knock that is killing the car once it shoots lean.

It was not doing this one month ago. I tried messing with the RRFPR setting. Is it counter clockwise (tightening the spring) that gives less fuel? It's possible that I am trying to adjust this thing wrong which is causing it to allow less fuel.

I have a dyno day scheduled in June and would like to get this issue resolved before then.

Thanks!

Install a fuel pressure gauge.

I have check fuel pressure at idle. The car drives fine normally.

Are you saying I need to check fuel pressure at WOT?

Yeah, run a hose out from under the hood to a gauge you can read through the windshield. You'll be able to monitor your pressure and properly adjust your FMU to compensate or diagnose other delivery problems.

Ok. I want to check the pressure before the rail, right? Or do I want to put the gauge after the oem fpr and before the cartech unit?

I found this on the website. I wonder if my pump is starting to fail. I have had a walb. 255 sitting around for a while waiting ot go in. Maybe it's time. Or maybe I need to rebuild my rrfpr.. it's got to be almost 15 years old now.

Checking Pump Pressures:
A brief check of the maximum fuel pressure available should also be done at idle. This is essentially determining the pump’s pressure capability. None of the regulators can force a pump past it maximum pressure potential. With a pair of pliers, squeeze the fuel line shut that connects our regulator to the original fuel pressure regulator. When squeezed shut, the pump will be forced to maximum output. Make sure the pressure available is consistent with your intentions. In all cases, the pressure must show, in this idle test, to be about 10 psi higher than the desired fuel pressure, as the available pressure under real load conditions will be less than that measured at idle. This test does not actually prove the pump to be adequate under boost, but if it doesn’t pass this test, it is certainly a waste of time to continue with the same pump. In general, do not try to exceed 100-110 psi fuel pressure.

The maximum fuel pressure is controlled by the needle valve and must be determined while driving the car under boost. Start with the needle valve closed, which is fully clockwise. It is unlikely the regulator will need this adjustment, but the test also serves the purpose of proving the pump will do the job needed. A weak fuel pump will cause a drop in fuel pressure as the engine is revved higher. If the pump cannot maintain the desired psi to the engine redline, it is not in satisfactory condition to feed the turbo/sc engine and must either be replaced or supplemented with an auxiliary pump.

Also, what kind of fuel pressure should I expect at boost? From what I remember, I am around 40PSI at hot idle.

Fuel pressure under boost will vary depending on your RRFPR setting. You should see fuel pressure rise with manifold pressure. If fuel pressure does not rise significantly under boost or drops as revs increase you have a fuel supply issue.

Thanks for the replies.

Here is the latest update after a drive I just took with a friend helping monitor all the gauges.

I am mid 11s A/F but I don't hear the TiaL WG opening. It has a .7 bar spring so it should be fully opened at 10 PSI. It doesn't matter how my boost controller is set, I am seeing almost 20 PSI on the gauge. The car is running out of fuel and cutting throttle. Stock pump can't handle that much air I guess.

I need to figure out why the WG isn't opening. What cause the WG not to open? Vac at idle is perfect at -18.

Another possibility is that my boost controller is stuck open all the way, causing it to stay at max setting (17 PSI).

What kind of boost controller are you using and how is it plumbed into the system? Is the boost controller applying pressure to the lower chamber of the TiAl? Is the upper chamber open to atmo? What happens if you run the WG signal line right to the WG bypassing the boost controller?

Does the wastegate hold pressure? I would try blowing into the signal line. If you can blow through the wastegate that would be your problem. The TiAL is a very good wastegate but the diaphragm is a potential maintenance item. Also check the signal line fitting into the wastegate and the integrity of the line itself. If the wastegate and signal line are holding pressure that points to a problem upstream with the boost control system.

You should get many years of service from a diaphragm but eventually they can harden and split. The only one I've ever seen actually fail went through a ceramic coating, which subjected it to heat far in excess of what it would see in normal use.

Sounds like a Wastegate issue - or lack thereof...
When and where you heading to the dyno? I am trying like hell to get mine to balanced within the next 2 weeks.... But I've been trying for a while now! Lmk if you need some parts- I may have something that you can swap for trouble shooting.

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mooseheadm5 wrote:Yeah, run a hose out from under the hood to a gauge you can read through the windshield. You'll be able to monitor your pressure and properly adjust your FMU to compensate or diagnose other delivery problems.

Never run a mechanical fuel gauge in the car. Outside against the ws is OK.

Duke wrote:

mooseheadm5 wrote:Yeah, run a hose out from under the hood to a gauge you can read through the windshield. You'll be able to monitor your pressure and properly adjust your FMU to compensate or diagnose other delivery problems.

Never run a mechanical fuel gauge in the car. Outside against the ws is OK.

Yes, that's why I said so you can read it through the windshield.

mooseheadm5 wrote:Yes, that's why I said so you can read it through the windshield.

I know, just wanted to make its clear to all. We know better, others.....not so much.

Roger that.

Found the problem... too bad it was after I swapped the stock WG back on.

It was the vac line that runs from the magnetic valve to the turbo. It had popped off. Car is running like a champ again.


Thanks for all the replies.

Brad D. wrote:What kind of boost controller are you using and how is it plumbed into the system? Is the boost controller applying pressure to the lower chamber of the TiAl? Is the upper chamber open to atmo? What happens if you run the WG signal line right to the WG bypassing the boost controller?

Team745 boost controller. In-tube is from the top port on WG. Out-tube runs to the pipe connecting the IC to turbo. I did bypass the boost controller, issue was still happening which was why I assumed the WG was the issue. Wish I had checked all the vac lines first!

I am still running out of fuel when boosting over .7 bar so I will be installing the inline 255 this weekend.

pressure testing the whole turbo and intake side of the engine including charge piping and intercooler is an extremely valuable tool that everyone should use with a forced induction vehicle. it really should be done every few thousand miles as a maintenance step also. it can quickly and easily help find little issues like this.

sideways7 wrote:pressure testing the whole turbo and intake side of the engine including charge piping and intercooler is an extremely valuable tool that everyone should use with a forced induction vehicle. it really should be done every few thousand miles as a maintenance step also. it can quickly and easily help find little issues like this.

Interested in how you would do that. Is that like a smoke test or something else?

Yes, How would you pressure test all of that?

Next time, I will know to check all vac lines on turbo side first. Any other leak will show on the vac gauge.

BTW SicStang03, I received your parts. Thanks very much for the nice service.

you remove the turbo inlet tube at the compressor inlet. you then install a cap with an air fitting in it. (pvc pipe caps work great for this) the air fitting can either be an airline fitting if you have an air compressor or a shrader valve to use a bike pump or equivalent. if you are using a compressor, it should be far enough from the car that you can hear leaks around the engine. you will also need an air regulator using the compressor. once you are set up, you gradually add air to the system and start to look and listen for leaks. a spray bottle with soapy water can be helpful too. you will have a leak at the crankcase breather.... this is normal, and the more blow by you have the bigger that leak will be. do not cap that leak or the dipstick may blow out. you will have to work down the line of leaks. air will find it's way out the biggest leak first... fix that and then it will be leaking out the next biggest leak. this is time consuming the first time you do it to a car. but, once everything is sealed, it won't be that bad the next time. doing this regularly will make sure your car is making the most power it can and that your tune stays as consistant as possible.

demetk wrote:BTW SicStang03, I received your parts. Thanks very much for the nice service.

Great! thanks for the business

sideways7 wrote:you remove the turbo inlet tube at the compressor inlet. you then install a cap with an air fitting in it. (pvc pipe caps work great for this) the air fitting can either be an airline fitting if you have an air compressor or a shrader valve to use a bike pump or equivalent. if you are using a compressor, it should be far enough from the car that you can hear leaks around the engine. you will also need an air regulator using the compressor. once you are set up, you gradually add air to the system and start to look and listen for leaks. a spray bottle with soapy water can be helpful too. you will have a leak at the crankcase breather.... this is normal, and the more blow by you have the bigger that leak will be. do not cap that leak or the dipstick may blow out. you will have to work down the line of leaks. air will find it's way out the biggest leak first... fix that and then it will be leaking out the next biggest leak. this is time consuming the first time you do it to a car. but, once everything is sealed, it won't be that bad the next time. doing this regularly will make sure your car is making the most power it can and that your tune stays as consistant as possible.

Very nice. Thanks very much for the description. I'm going to try this on the e34.

That's my favorite thing about Megasquirt. No need to leak test intake plumbing. Whatever makes it to the manifold is accounted for.

the problem with running your car with leaks is that you have a lot of air leaking in different directions, under different conditions. and no matter what kind of thermodynamics degree someone may have or flow analysis software... you can't account for all of the little changes that occur in all conditions. for example under vacuum when it is cold out you may have a lot of air leaking in and making your car idle higher, but then when it warms up the rubber that is leaking expands and then your idle drops. it makes the whole system inconsistent for tuning. checking for leaks is the proper way to do it regardless of how you are metering air. the other problem you run into is that if you have a bunch of pressure leaks under boost, the turbo has to spin at a faster speed to make the targeted boost. if you are running a closed loop electronic boost control, this becomes a huge headache with leaks. since the turbo is spinning much faster, it puts a lot more wear on it also. also, since the turbo is spinning faster it creates more heat, which then reduces power.
you will be surprised what you can find pressure testing. something that you may never expect to leak, may be a huge leak at 1psi. please trust me on this. i pressure test turbo vehicles everyday and clean up other performance shops messes when they don't pressure test. it does make a difference.

Dyno results?

Nebraska_e28 wrote:Dyno results?

272/350 @ 8psi. -013 Motronic, 3" exhaust, K27 with GT35R wheel.