Volvo 740 B230ET Boost then Stalls

Hello All,

I need some advice, whenever I depress the throttle, the boost comes in nicely for a couple of seconds and suddenly the engine will stall??? The boost does not exceed 7psi.

When I run boost up to 10psi with my HKS EVC1, it will stall even faster especially I WOT.

My car is a stock 1989 740 B230ET Intercooler Turbo, which runs on a Motronic ECU.

Please advice...

sounds to me like a fuel problem. you hit a certain boost level and then your fuel cant keep up with the demand. it would make sense for it to happen faster if you crank up your boost.

so thats what i think, now why? not sure.

*edit, you get motronic on those buggers?! we didnt get that till '92 here.

cascherman,

I have tried installing a 960 In tank Fuel Pump, but the Secondary Pump got very noisy.

In my case, the car doesnt feel like a Fuel-Cut or Insufficient Fuel Supply. It reaches 2,500 rpm to 3,500 rpm and it will stall suddenly without warning!!!

Checked plugs? Make sure they are like .03" or less

Its the fuel cut off
when boost gets up to about 10+psi
cuts fuel
theres a littleswitch under the dash
a hose going to a pressure switch and two wires
DO a search
If you got balls and not scared to send a rod out the block
pull the hose off and plug it


I Beleave

Plugs are OEM volvo meant Volvo B230ET.

I have changed all my vacuum hoses to silicon, but at the end of the hose under the dash is connected to a stock boost meter.

The motronic ECU doesnt seem to have a Pressure switch under the dashboard.

HOHO.. I would love to unplug the Hose off...

BTW do the Turbos produce a strange whinny sound when the boost kicks in??? Or is it boost leaking from the Manifolds

kelfo said:

Plugs are OEM volvo meant Volvo B230ET.

Click to expand...

Yeah, what are the gaps set at?

The gaps are standard... original from packing...
The Spark Plugs are only 2 days old.
The problem has been with me since I got the car 2 years ago.

Motronic B230ET's have two boost cuts. One is the pressure switch under the dash, which breaks the fuel pump relay circuit. The other is programmed into the ECU, and if the airflow meter senses more than a certain amount of air entering the engine, it cuts power to the ignition and injectors until the amount of air drops again.

This sounds like your problem. On my car ('85 B230ET) this will happen occasionally at stock boost, fairly often at my current boost setting of 9psi, and at anything above 10psi the car becomes almost undrivable. Fitting an aftermarket chip to your Motronic ECU gets around this problem, this is the next thing on my list after I get the Supra gearbox in.

For some unknown reason it becomes much worse if you put lower octane fuel in the car, I once put regular unleaded in the car and it became almost undrivable, stalling at part throttle rather than only at WOT.

One way to see if this is the problem is to hook up a fuel pressure gauge and attach it to the mirror, and take it for a drive. If you find that the fuel pressure doesn't drop, and in fact rises a couple of psi when the engine cuts, this tells you that the pumps are running the whole time, even when the engine cuts, and therefore it isn't a fuel supply issue.

Another test is to pop the cover off the fuel pump relay and jam the contacts closed with a toothpick or similar, take it for a drive, and see if it still stalls.

Angus242164...

Thank you for your advice, its been most enlightening. I will work along your suggestion to sort out the problem. Like what you describe, the car symptoms are very similar. Any Suggestions where I can get an aftermarket chip?

I have a Fuel Regulator Gauge in the engine, now is to test it while on load. My current FC is really bad, one full tank 55L, with mixed driving, my distance travelled is about only 200km.

What if I replace with a Walbro 255lph in-Tank Fuel Pump and remove the other 2 Volvo pumps, would it solve my problems?

kelfo said:

I have a Fuel Regulator Gauge in the engine, now is to test it while on load. My current FC is really bad, one full tank 55L, with mixed driving, my distance travelled is about only 200km.

Click to expand...

Holy hell!! I get about 200km of mostly town driving out of about 17L and I thought that was bad!

There is something else going on other than a fuel cut, does the car spew blacksmoke out the exhaust? with that mileage it should be.
Check to make sure you don't have a fuel leak somewhere after the main pump, loss of fuel line pressure could give the same symptoms as a fuel cut.

kiwibrick

So far my can does not spew black smoke although I do suspect I have a faulty AFM. No sign of Fuel Leaks anywhere.

However, I wonder if the stock BOV leaks, will the AFM open to cause a rich mixture?

My Garett TD03 produces a strange whiny sound, I wonder if its leaking??? Especially when I have 4 passengers onboard, the car acts like it has hiccups...

At times I feel like changing the engine to a 1JZ-GTE TT. *sign*

I would still say that checking the fuel pressure while driving would be a good start, and it would also be a good idea to check for any leaks in any of the intake hoses and vacuum hoses.

The coolant temperature sensor could be faulty, causing it to run rich all the time. I would check the resistance of the sensor circuit at the ECU plug and compare to specs.

The airflow meter could be faulty as well, but I'm not sure exactly what symptoms this would give.

If possible I would also find a workshop that has an exhaust gas analyser, and see what your mixture is like, and adjust the idle mixture with the screw on the airflow meter, if it is too rich that could affect fuel consumption.

A Walbro fuel pump will only be of benefit if the stock fuel pump can't supply enough pressure. If the fuel pressure doesn't drop when the engine is at high rpm/full boost then your current pumps are adequate.

Kelfo,

Is your turbine covered with oil/sludge? If the car has hiccups it could be gasping for air. What air filter are you using? I used to have those hiccups when boosting at 0.9bar and only having a K&N drop in air filter. If I drop the boost back to 0.3, it'll be ok. Once I changed it to a HKS open pod filter and raised the boot to 0.9 again, those hiccups were gone. When you mention stalling, is that the hiccups or did the motor stalls and dies? If it's just giving hiccups, try giving more air instead of fuel. This is just my 2 cents. and check your O2 sensor for the high fuel consumption.

Angus242164,

I have replaced all the old rubber hoses and upgraded to the silicon hoses about a month back. As for now, I doubt theres any leakage.

Today I ripped apart the AFM, and cleaned it with Half a Can of Philips Contact Cleaner. The previous setting for the AFM was only 1/2 turn from close, so I re-adjusted the setting to 2 and 3/4Turn from close The FC has Improved, but I have yet to comment as I still have half-tank of fuel left. I noticed on stock boost the car is behaving alright and it does'nt stall anymore. Only when I turn up the boost at 7.5psi - 10psi the motor still stalls as its revving.

The other thing I did was tighten the Stock BOV by 1 turn. The turbo doesnt sound so whiny, maybe the stock BOV is leaking.

Hello Mojam,

Nice to see you here...

My car runs on a Motronic ECU and it doesnt have an o2 sensors. I am using an OPEN POD air Filter. The turbo is Pretty Clean, minimal oil or sludge in it. I think I need to upgrade to an Aftermarket Chip.

I have also searched under the dash, traced all the hoses, but i did'nt find the Pressure Regulator. I doubt the Malaysian Volvo 740 TIC comes with the Pressure Regulator.

The problem now is I cannot arm the HKS EVC1, the minute the boost goes up, it will rev up and stall suddenly. (Sudden Death).

Tomorrow, I will run a Fuel Pressure Gauge to the windscreen to monitor the Fuel Pressure.

I will keep you guys posted. In the meantime, thank you for all your advice and help!!!

kelfo said:

Hello Mojam,

Nice to see you here...

My car runs on a Motronic ECU and it doesnt have an o2 sensors. I am using an OPEN POD air Filter. The turbo is Pretty Clean, minimal oil or sludge in it. I think I need to upgrade to an Aftermarket Chip.

I have also searched under the dash, traced all the hoses, but i did'nt find the Pressure Regulator. I doubt the Malaysian Volvo 740 TIC comes with the Pressure Regulator.

The problem now is I cannot arm the HKS EVC1, the minute the boost goes up, it will rev up and stall suddenly. (Sudden Death).

Tomorrow, I will run a Fuel Pressure Gauge to the windscreen to monitor the Fuel Pressure.

I will keep you guys posted. In the meantime, thank you for all your advice and help!!!

Click to expand...

Mine didn't come with pressure regulator either... I was advised to install one on my car but opted not to. Having unichip on might solve the issue but don't quote me on that. It's best to consult with Lim of RS Impressive for that. Your EVC might be sending the wrong signals to the motor, that might have caused the stall. Other than that, I can't seem to think what might be wrong with it.

Mojam...

With the Motronic ECU, I reckon the Mapping Perimeters are quite limited. So far with boost above 7.5psi, it already exceeds the perimeters of the mapping.

With the EVC on, it can work for a short burst only before the motor stops suddenly... but if you let the throttle off fast enough, the engine will recover from the stall.. Weird!!!

Unichip is pretty expensive, especially from TBL... No offence!!! I am sure there are cheaper alternatives.

The question is... DOES anybody know of cheaper alternatives???

kelfo said:

Mojam...

With the Motronic ECU, I reckon the Mapping Perimeters are quite limited. So far with boost above 7.5psi, it already exceeds the perimeters of the mapping.

With the EVC on, it can work for a short burst only before the motor stops suddenly... but if you let the throttle off fast enough, the engine will recover from the stall.. Weird!!!

Unichip is pretty expensive, especially from TBL... No offence!!! I am sure there are cheaper alternatives.

The question is... DOES anybody know of cheaper alternatives???

Click to expand...

No offence taken. Yeah, there are cheaper alternative like Eurosport Tuning's Powerchip which will set you back $390 (without installation/tuning). The thing is, it's listed for b230ft engine. Ask them if they cater to b230et's. Then there's Superchip (yet another piggyback), though I can't recall the quoted price the shope mentioned to me. Known ECU makers such as Rica and MTE won't do senior motors. Tell me how it works out for you aight?

There is the Viking chip, sold by JP Styling in Sweden, for the B230ET, and also a chip made by BSR in Sweden. I have also heard of a chip made by "Superchips" for the B230ET, but haven't looked into it.

The Viking and BSR chips were around $200-250AUD including postage when I last checked.

I'm not aware of any other chips to suit the B230ET.