HELP! Supercharger troubleshooting HELP!

Fast510 · 12-07-2008, 03:35 PM

I have been having problems with my MR2SC over the last few weeks. Car runs fine when cold and even for a while when its warm. Sometime after “heat soaking” the engine bay it seems that it won’t make boost. Idles fine, revs fine with no load but when you try to move the car it falls on its face and won’t go. Motor doesn’t rev while in gear with a load. Push in the clutch and revs great, start to let out the clutch and it wants to die. The first time this happened it was a vacuum line that fell off and I have replaced said line with new to make sure it didn’t happen again, and yet I have the same symptoms. Like I said it was the vacuum line to a VSV from the Fuel pressure regulator last time it did this but that is all now replaced with new line. Is there a way to test those VSV’s? I was able to get the car home the next day as it seems to drive just fine when its cold and in fact made the whole 30min trip no problem. Today I went out there and drove it around the neighborhood just fine with no problems so I let it idle in the driveway for awhile then went out sure enough it started doing it again. Anybody have any ideas? I did a full tune-up just a little bit ago with new Factory Toyota cap, rotor, plugs (NGK) and wires are fine although I do have a spare set just in case. I also washed the engine bay a few weeks ago but its been running fine since then and I pulled the plug wires and distributor cap and used compressed air to blow them dry before starting the car so I really doubt that it would be water anywhere. Especially since it ran fine for a few weeks before this problem started happening.

Any tips/hints/ welcome!

P.S. If you are in the NW area or will be, I have beer on tap, and plenty of brats or could order pizza if someone knows how to fix or troubleshoot a Supercharged car in person…

Mike Masson
1989 Toyota MR2SC
1989 Toyota MR2 20valve silvertop daily driver
1985 Toyota MR2 hardtop (for sale)
2001 Suzuki DRZ400S
1977 Yamaha RD400 (2stroke for sale)
1972 Datsun 510 2door V6 powered 4wdisc brakes LSD ect ect (for sale)

Jackstand Queen · 12-08-2008, 03:14 PM

Mine had a running problem just like yours. It could be caused by dozens of problems.

Let's start with the likely candidates

First test your fuel pressure regulator. Unplug the line, take an ear wash bulb, and use it to create vacuum and pressure on the line going to the FPR. At idle, both actions should cause the idle RPM to react slightly. Maybe a hundred RPM increase or so. If no resonse, get a new FPR.

Next, I'd look at temperature sensors. There are two, one for coolant temp and one for air temp. The coolant temp sensor is located on the driver's side of the head. Hook up an ohmeter and compare the resistance reading to a chart based on the temperature of the head. Living in the NW myself (SW Oregon), corrosion is a HUGE problem. Likely, the air temp terminals in the AFM connector is corroded badly. Get a nail file, some grit without chlorine in it (like not comet) and file and scrub that terminal clean. Also test the AFM air temp sensor with an ohmeter using ambient air temp and the chart.

You also might want to pull the codes from your ECU using the low tech method of shorting two terminals out on the test connector, and then count the flashes on the Eng. light to pull the codes.

There's a recent post on this board about where to download an Sc manual online. That could be step 1, if you don't already have one.

I feel your pain.

Fast510 · 12-14-2008, 03:50 AM

ok even though we got 4-5 inches of snow today in the Northwest Puget Sound... I got out to swap the snow tires on the MR2's and check for engine light/codes. None doesn't see any problems and of course it ran fine around the neighborhood. Don't know if its the cold or just a really PIA problem that comes and goes when it feels like it but I couldn't get it to act up tonight. Really didn't try too hard with the weather and all though. It may have to wait for a few weeks as the forcast is for record cold temps and as I think the problem is a electrical issue when the engine bay heat soaks... may not be able to get the problem to return for a while. Thankfully I have another MR2 to drive in the snow

Fast510 · 12-14-2008, 03:56 AM

I will try testing the FPR maybe monday as the Seattle Motorcycle show last day is tomorrow and a few of the MR2/bike friends are going. Might get time later in the evening as well since I don't work monday either.

Jackstand Queen · 12-14-2008, 04:07 PM

This weather dampens my work activities too. No nice, warm garage to work in. Sigh . . .. it sucks to be me.

Focused · 02-28-2009, 10:35 PM

I had the same problem with my 88' SC, as soon as the car came up to temp. it would loose all boost pressure and I would have to "peddle" the throttle to get up to speed. This happened whenever the supercharger would come on at about 3500-4000 rpm. At first, I the one of the injectors was clogged and tuned the car(plugs, wires, distributor cap, rotor button, etc.) but same problem still existed. I read this and similar post and decided to clean the A.F.M. which had some corrosion inside and voila she runs like a champ now!!! I hope this helps, good luck.

12-07-2008, 03:35 PM	#1 (permalink)
Fast510 No Skills Join Date: May 2005 Location: Lake Stevens, WA Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	HELP! Supercharger troubleshooting HELP! I have been having problems with my MR2SC over the last few weeks. Car runs fine when cold and even for a while when its warm. Sometime after “heat soaking” the engine bay it seems that it won’t make boost. Idles fine, revs fine with no load but when you try to move the car it falls on its face and won’t go. Motor doesn’t rev while in gear with a load. Push in the clutch and revs great, start to let out the clutch and it wants to die. The first time this happened it was a vacuum line that fell off and I have replaced said line with new to make sure it didn’t happen again, and yet I have the same symptoms. Like I said it was the vacuum line to a VSV from the Fuel pressure regulator last time it did this but that is all now replaced with new line. Is there a way to test those VSV’s? I was able to get the car home the next day as it seems to drive just fine when its cold and in fact made the whole 30min trip no problem. Today I went out there and drove it around the neighborhood just fine with no problems so I let it idle in the driveway for awhile then went out sure enough it started doing it again. Anybody have any ideas? I did a full tune-up just a little bit ago with new Factory Toyota cap, rotor, plugs (NGK) and wires are fine although I do have a spare set just in case. I also washed the engine bay a few weeks ago but its been running fine since then and I pulled the plug wires and distributor cap and used compressed air to blow them dry before starting the car so I really doubt that it would be water anywhere. Especially since it ran fine for a few weeks before this problem started happening. Any tips/hints/ welcome! P.S. If you are in the NW area or will be, I have beer on tap, and plenty of brats or could order pizza if someone knows how to fix or troubleshoot a Supercharged car in person… Mike Masson 1989 Toyota MR2SC 1989 Toyota MR2 20valve silvertop daily driver 1985 Toyota MR2 hardtop (for sale) 2001 Suzuki DRZ400S 1977 Yamaha RD400 (2stroke for sale) 1972 Datsun 510 2door V6 powered 4wdisc brakes LSD ect ect (for sale)

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12-08-2008, 03:14 PM	#2 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 840 Thanks: 75 Thanked 64 Times in 60 Posts iTrader Rating: (1/100% )	Mine had a running problem just like yours. It could be caused by dozens of problems. Let's start with the likely candidates First test your fuel pressure regulator. Unplug the line, take an ear wash bulb, and use it to create vacuum and pressure on the line going to the FPR. At idle, both actions should cause the idle RPM to react slightly. Maybe a hundred RPM increase or so. If no resonse, get a new FPR. Next, I'd look at temperature sensors. There are two, one for coolant temp and one for air temp. The coolant temp sensor is located on the driver's side of the head. Hook up an ohmeter and compare the resistance reading to a chart based on the temperature of the head. Living in the NW myself (SW Oregon), corrosion is a HUGE problem. Likely, the air temp terminals in the AFM connector is corroded badly. Get a nail file, some grit without chlorine in it (like not comet) and file and scrub that terminal clean. Also test the AFM air temp sensor with an ohmeter using ambient air temp and the chart. You also might want to pull the codes from your ECU using the low tech method of shorting two terminals out on the test connector, and then count the flashes on the Eng. light to pull the codes. There's a recent post on this board about where to download an Sc manual online. That could be step 1, if you don't already have one. I feel your pain.

12-14-2008, 03:50 AM	#3 (permalink)
Fast510 No Skills Join Date: May 2005 Location: Lake Stevens, WA Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	ok even though we got 4-5 inches of snow today in the Northwest Puget Sound... I got out to swap the snow tires on the MR2's and check for engine light/codes. None doesn't see any problems and of course it ran fine around the neighborhood. Don't know if its the cold or just a really PIA problem that comes and goes when it feels like it but I couldn't get it to act up tonight. Really didn't try too hard with the weather and all though. It may have to wait for a few weeks as the forcast is for record cold temps and as I think the problem is a electrical issue when the engine bay heat soaks... may not be able to get the problem to return for a while. Thankfully I have another MR2 to drive in the snow

12-14-2008, 03:56 AM	#4 (permalink)
Fast510 No Skills Join Date: May 2005 Location: Lake Stevens, WA Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	I will try testing the FPR maybe monday as the Seattle Motorcycle show last day is tomorrow and a few of the MR2/bike friends are going. Might get time later in the evening as well since I don't work monday either.

12-14-2008, 04:07 PM	#5 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 840 Thanks: 75 Thanked 64 Times in 60 Posts iTrader Rating: (1/100% )	This weather dampens my work activities too. No nice, warm garage to work in. Sigh . . .. it sucks to be me.

02-28-2009, 10:35 PM	#6 (permalink)
Focused No Skills Join Date: May 2008 Posts: 9 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I had the same problem with my 88' SC, as soon as the car came up to temp. it would loose all boost pressure and I would have to "peddle" the throttle to get up to speed. This happened whenever the supercharger would come on at about 3500-4000 rpm. At first, I the one of the injectors was clogged and tuned the car(plugs, wires, distributor cap, rotor button, etc.) but same problem still existed. I read this and similar post and decided to clean the A.F.M. which had some corrosion inside and voila she runs like a champ now!!! I hope this helps, good luck.