Engine Hesitates - Page 2

Dave In Indy · 08-21-2009, 01:23 PM

Quote:

Originally Posted by toy4tao

What year is your mr2? I think this might solve your problem...
MR2 Owners Club Message Board™

Drive train is a 1988 the car is a 1989. I can't access that link since I don't have an account there.

Jackstand Queen · 08-21-2009, 06:03 PM

The main upshot of that link for Dave in Indy is:

check the terminals on your AFM for corrosion.

I strongly recommend against opening up your AFM's guts and making adjustments to it, as the link discusses.

Dave In Indy · 08-21-2009, 09:30 PM

Crawled under it tonight to replace the alternator since the battery goes bad if the car sits for more then a day. And of course the car started bogging again today on the way home. Guess what I found? A bad T-VIS solenoid. Completely clogged, and broke in two when I took the hose off. So I'm going to replace that, and hoepfully that'll help. I think the T-VIS was on at all times. Does that make sense from what I've been seeing? I appreciate the help everyone has been offering. Thanks!

Jackstand Queen · 08-22-2009, 01:21 AM

It makes a world of sense. Since hesitation has so many possible causes, you just have to go through it piece by piece, from most likely to least, until you get it.

tjmr2 · 08-22-2009, 01:33 AM

The TVIS fails open ~ as the butterflies do not operate since the vacuum in the system and the reservoir is what holds them closed.

TVIS doesn't activate until 4350 RPM. The theory behind TVIS is to achieve a higher cylinder charge due to intake air speed. So they block off 4 of the 8 ports under 4350 RPM and open the other 4 once the engine needs them to breathe.

If the TVIS is - has failed open the engine will just not have the torque below 4350 like it should. It will still run, and run pretty well, but not like it should. I messed with my TVIS for over a year after I rebuilt my 16 valve before I got it right. My engine never stumbled or hesitated, but I could tell it wasn't quite right.

Personally I don't think the butterfly part of the TVIS is causing your problem and would look more at vacuum hoses.

Could be the Vacuum Switching Valve (VSV) for the TVIS was a major vacuum leak and not switching the TVIS at the same time.

From your last post if you just plug the vacuum line that led to the TVIS VSV you might see the bog - hesitation disappear. Low end torque won't be what it could be, but that would narrow your search.

Dave In Indy · 08-22-2009, 06:53 PM

Fixed it! Runs great no. I should have known when I saw the welding blob on the pulley. The yahoo that owned the car aparently broke the crank pulley or something and welded the two together. The timing marks were way the heck off. Retimed it the old school way and the darn thing flys. That little car move pretty good for being 22 years old.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

08-21-2009, 06:03 PM	#22 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 840 Thanks: 75 Thanked 64 Times in 60 Posts iTrader Rating: (1/100% )	The main upshot of that link for Dave in Indy is: check the terminals on your AFM for corrosion. I strongly recommend against opening up your AFM's guts and making adjustments to it, as the link discusses.

08-21-2009, 09:30 PM	#23 (permalink)
Dave In Indy Some Skills Join Date: Jun 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (0/0% )	Crawled under it tonight to replace the alternator since the battery goes bad if the car sits for more then a day. And of course the car started bogging again today on the way home. Guess what I found? A bad T-VIS solenoid. Completely clogged, and broke in two when I took the hose off. So I'm going to replace that, and hoepfully that'll help. I think the T-VIS was on at all times. Does that make sense from what I've been seeing? I appreciate the help everyone has been offering. Thanks!

08-22-2009, 01:21 AM	#24 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 840 Thanks: 75 Thanked 64 Times in 60 Posts iTrader Rating: (1/100% )	It makes a world of sense. Since hesitation has so many possible causes, you just have to go through it piece by piece, from most likely to least, until you get it.

08-22-2009, 01:33 AM	#25 (permalink)
tjmr2 Cage Fighter Join Date: Jan 2008 Location: Colorado Posts: 410 Thanks: 0 Thanked 62 Times in 59 Posts My Google Map iTrader Rating: (0/0% )	The TVIS fails open ~ as the butterflies do not operate since the vacuum in the system and the reservoir is what holds them closed. TVIS doesn't activate until 4350 RPM. The theory behind TVIS is to achieve a higher cylinder charge due to intake air speed. So they block off 4 of the 8 ports under 4350 RPM and open the other 4 once the engine needs them to breathe. If the TVIS is - has failed open the engine will just not have the torque below 4350 like it should. It will still run, and run pretty well, but not like it should. I messed with my TVIS for over a year after I rebuilt my 16 valve before I got it right. My engine never stumbled or hesitated, but I could tell it wasn't quite right. Personally I don't think the butterfly part of the TVIS is causing your problem and would look more at vacuum hoses. Could be the Vacuum Switching Valve (VSV) for the TVIS was a major vacuum leak and not switching the TVIS at the same time. From your last post if you just plug the vacuum line that led to the TVIS VSV you might see the bog - hesitation disappear. Low end torque won't be what it could be, but that would narrow your search.

08-22-2009, 06:53 PM	#26 (permalink)
Dave In Indy Some Skills Join Date: Jun 2009 Posts: 61 Thanks: 1 Thanked 3 Times in 3 Posts iTrader Rating: (0/0% )	Fixed it! Runs great no. I should have known when I saw the welding blob on the pulley. The yahoo that owned the car aparently broke the crank pulley or something and welded the two together. The timing marks were way the heck off. Retimed it the old school way and the darn thing flys. That little car move pretty good for being 22 years old.