3.2 Hesitation - I'm going nuts throwing parts at it! Help me look for vacuum leaks!

[Dubbin']

Originally Posted by scarceller

That's OK, do you possibly have anyone in your area with a 84-89 3.2L if so you can take your DME and put it in that other car to see if the problems move to the other car. I usually don't recommend the inverse, do not put a good DME in a questionable car. Where are you located?

Here's a thread I wrote up and shows bad joints and howto properly repair them. Even in the high res pics it's hard to tell those 3 are cracked:
http://forums.pelicanparts.com/porsche-911-technical-forum/652375-dme-bad-solder-joint-repair.html

A friend of mine has a 84 Targa with a 85 3.2 Motronic swap in it that runs great. He thinks his DME is an 84 and has a 'jumper' soldered on and a Steve Wong chip. Is it worth a shot considering his runs correctly?

Thanks,
Mark

[scarceller]

You can put your DME directly into that car, your DME will work perfectly in that car. I'd try that to rule out any DME issues. If you find the DME is the issue I can help but one step at a time.

Don't even take his DME out from under the seat! Simply unplug the large cable from the DME in his car leaving his DME bolted down as is. Then just plug the cable into your DME and place it safely in front of the existing DME or on a towel ontop of his existing DME. Your DME does not need to be bolted down to test it in his car, just plug it in and take for a drive. Will take no more than 2 minutes to get it plugged in. If you like also bring your DME relay along and test that also in his car, first just your DME then if all is well put in your relay and test with both your relay and the DME together.

Any 84-89 DME will work in any 84-89 car. Sure some DMEs are diffrent over the years but the engine and wiring is the same. You can put a 84 DME in a 89 car or visa-versa.

The Jumper you are talking about was most likely so that his 84 2K DME could run a 24pin 4K chip instead of a 24pin 2K chip, very common upgrade. Another common upgrade I do all the time is upgrade DMEs to the latest 88-89 8K 28pin chip. But having these upgrades does stop a DME from working in any 84-89 car.

Originally Posted by Dubbin'

A friend of mine has a 84 Targa with a 85 3.2 Motronic swap in it that runs great. He thinks his DME is an 84 and has a 'jumper' soldered on and a Steve Wong chip. Is it worth a shot considering his runs correctly?

Thanks,
Mark

[scarceller]

I think your next 2 steps are:
1 - in your car unplug the stock O2 if it's plugged in and see if it makes a diffrence
2 - take your existing DME and DME relay and install them in the other test car to rule those components out.

[Dubbin']

Originally Posted by scarceller

You can put your DME directly into that car, your DME will work perfectly in that car. I'd try that to rule out any DME issues. If you find the DME is the issue I can help but one step at a time.

Don't even take his DME out from under the seat! Simply unplug the large cable from the DME in his car leaving his DME bolted down as is. Then just plug the cable into your DME and place it safely in front of the existing DME or on a towel ontop of his existing DME. Your DME does not need to be bolted down to test it in his car, just plug it in and take for a drive. Will take no more than 2 minutes to get it plugged in. If you like also bring your DME relay along and test that also in his car, first just your DME then if all is well put in your relay and test with both your relay and the DME together.

Any 84-89 DME will work in any 84-89 car. Sure some DMEs are diffrent over the years but the engine and wiring is the same. You can put a 84 DME in a 89 car or visa-versa.

The Jumper you are talking about was most likely so that his 84 2K DME could run a 24pin 4K chip instead of a 24pin 2K chip, very common upgrade. Another common upgrade I do all the time is upgrade DMEs to the latest 88-89 8K 28pin chip. But having these upgrades does stop a DME from working in any 84-89 car.

I am Montreal, Quebec - Canada.

Ok perfect, thanks Sal, we will try that. my DME relay is new, it should not be an issue. I was swapping between the old and the new and there was no difference. I will also unplug the O2 sensor. I had unplugged it when I started trying to diagnose if it was culprit although I had not noticed any changes.

I will also put the black coil back and keep the silver one as a spare.

I have a picture of my DME although it is not HD nor is it a close up... It's only of the outside/top side. I can't say that I really enjoy playing around in there.

Thanks,
Mark

[scarceller]

Solder issues are usually on the other bottom analog board. That top board never really has solder issues.

Originally Posted by Dubbin'

Ok perfect, we will try that. my DME relay is new, it should not be an issue. I was swapping between the old and the new and there was no difference. I will also unplug the O2 sensor. I had unplugged it when I started trying to diagnose if it was culprit although I had not noticed any changes. I will also put the black coil back and keep the silver one as a spare.

I have a picture of my DME although it is not HD nor is it a close up... It's only of the outside/top side. I can't say that I really enjoy playing around in there.

Thanks,
Mark

[Dubbin']

Originally Posted by scarceller

Solder issues are usually on the other bottom analog board. That top board never really has solder issues.

It was unclear how to get to the bottom of the board without breaking anything. I'll test it in my friend's car and if it's faulty we'll go from there.

Thanks,
Mark

[scarceller]

You can even take the entire AFM and intake box and test in his car also, just do one part at a time. Moving the AFM is a bit more work but it's real nice having another well running car. Or move his AFM to your car. But start with the DME first.

Originally Posted by Dubbin'

It was unclear how to get to the bottom of the board without breaking anything. I'll test it in my friend's car and if it's faulty we'll go from there.

Thanks,
Mark

[Dubbin']

Originally Posted by scarceller

You can even take the entire AFM and intake box and test in his car also, just do one part at a time. Moving the AFM is a bit more work but it's real nice having another well running car. Or move his AFM to your car. But start with the DME first.

Scheduled to test out my DME on his car Saturday. I will start by testing my AFM with a multimeter. If it seems problematic I will test it on his car.

Thanks again for everyone's help. I will update the thread as time permits for me to diagnose items. Hopefully we will come to an eventual conclusion. I know this thread might become helpful for others and one thing I hated while searching through threads is that conclusions or fixes were often not posted.

[Dubbin']

Originally Posted by scarceller

I think your next 2 steps are:
1 - in your car unplug the stock O2 if it's plugged in and see if it makes a diffrence
2 - take your existing DME and DME relay and install them in the other test car to rule those components out.

DME tested on another car today. Car ran fine and the hesitation issues were not duplicated. It hesitated very faintly at one point but it was not the same hesitation that I've been having in my 3.2 and it might also been his car - no cat, HF muffler and cone intake- getting used to my stock ECU.

We tried to provoque the hesitation: WOT, partial throttle, hight revs etc. Nothing happened. I think we can ruie out the DME.

I did notice that while removing the DME after a 15-20 minutes drive it was warm. I figure this is normal?


Tomorow I will unplug O2 sensor, reinstall the black coil, test the AFM try and test or clean the ICV - WOT switch and throttle body. I will also visually check some rubber while I'm there.

Thanks,
Mark

[scarceller]

DME does get warm that's normal.
If you have not yet tested in your car with O2 unplugged that's the first thing you should try.
It's rare that a dirty TB or problematic ICV would cause hesitation under load. If the O2 unplugged doesn't change things then I suggest a Wideband O2 gauge so we know exactly what the mixture is set at. If your factory O2 sensor is healthy I have a poor mans procedure for checking mixture using the factory O2 sensor but you need to have a good quality Digital Volt meter that can measure 0-1 volt (0-1000 millivolts) very accurately, if you have that I help outline the procedure but one step at a time. Try putting back the black coil and unplugging the O2 sensor and report back.

Originally Posted by Dubbin'

DME tested on another car today. Car ran fine and the hesitation issues were not duplicated. It hesitated very faintly at one point but it was not the same hesitation that I've been having in my 3.2 and it might also been his car - no cat, HF muffler and cone intake- getting used to my stock ECU.

We tried to provoque the hesitation: WOT, partial throttle, hight revs etc. Nothing happened. I think we can ruie out the DME.

I did notice that while removing the DME after a 15-20 minutes drive it was warm. I figure this is normal?


Tomorow I will unplug O2 sensor, reinstall the black coil, test the AFM try and test or clean the ICV - WOT switch and throttle body. I will also visually check some rubber while I'm there.

Thanks,
Mark

[cabmandone]

Originally Posted by Dubbin'

DME tested on another car today. Car ran fine and the hesitation issues were not duplicated. It hesitated very faintly at one point but it was not the same hesitation that I've been having in my 3.2 and it might also been his car - no cat, HF muffler and cone intake- getting used to my stock ECU.

We tried to provoque the hesitation: WOT, partial throttle, hight revs etc. Nothing happened. I think we can ruie out the DME.

I did notice that while removing the DME after a 15-20 minutes drive it was warm. I figure this is normal?


Tomorow I will unplug O2 sensor, reinstall the black coil, test the AFM try and test or clean the ICV - WOT switch and throttle body. I will also visually check some rubber while I'm there.

Thanks,
Mark

I'd take the elbow off and visually inspect the TB. You can open the butterfly and look for any buildup inside the bore. I'd also make sure and do a really good once over on your vacuum lines. It still strikes me that you're getting unmetered air. When you say the car idles fine but does not drop when you pull the oil cap. I'd get your vacuum leaks sorted out then move forward. If you haven't made sure your vacuum connections are good you could chase your tail trying to find the problem IMO. Start with the easy/obvious problem and then dig deeper.

[Dubbin']

Hey guys,

Small update from yesterday.

1- Got the DME back into my car;
2- Replaced the silver coil with my previous black one;
3- Looked over some of the vacuum lines and found 2 (pictures bellow) from the oil fill neck that definitely look worn although not sure if they are leaking. I sprayed throttle body cleaner over them and around the intake runners and other rubber joints with no impact on the idle;




4- I looked over the vacuum hose going to the brake booster and it looked fine... Although I tested it with the outlined procedure on one of the threads linked in this discussion : pump the pedal-hold it firmly-start the car and the pedal should soften up and fall slightly to the floor. This did not happen. When I hold the pedal and start the car... nothing really happened - the pedal remains as high and as firm. When I try this with my Audi A6 the pedal falls and softens SIGNIFICANTLY;

5- I played with the injector harness and nothing happened. Played with the plugs to the injectors and the engine did not stumble;

6- I tried capturing the hesitation on video and got it. It might be hard for you guys to tell, but when the hesitation occurs I get surprised and let off the gas. To be honest it's kind of scary to provoke the hesitation... I prefer not doing it. I provoked the hesitation at WOT or close to it. As you will see it happens over 5,000 RPM.

I hope these videos work... the hesitation in this video happens at 5,600 RPM (3rd gear) and I let off the gas right away:

http://vid1029.photobucket.com/albums/y352/mark_farrell/porsche%201.mp4

Here is another video of the hesitation - again around 5,600RPM in 2nd gear:

http://vid1029.photobucket.com/albums/y352/mark_farrell/porsche%202.mp4

In this video it happens around 5,800RPM in 2nd gear again:

http://vid1029.photobucket.com/albums/y352/mark_farrell/porsche%203.mp4

7- Once warmed up, I popped the hood and started playing with the oil cap. I was actually wrong, there is a change in the idle when the cap is removed as you will notice in the video. The idle with the cap on is very stable at 1,000RPM, when the cap is removed it drops a few hundred rpm. Let me know if this change in idle is what is normal or should it be rougher?

http://vid1029.photobucket.com/albums/y352/mark_farrell/porsche%207.mp4

Here is a video in the engine bay of the idle while I play with the oil cap. As I put it on and off there is a difference. Might not be as significant as it should?

http://vid1029.photobucket.com/albums/y352/mark_farrell/porsche%206.mp4

I am having trouble with the 2 last videos? I only get sound. Let me know if it works for you guys.

Next step this week is to remove the airbox, test AFM, remove intake elbow and clean/inspect TB. Let me know what you guys think? Should I start looking at buying a Wideband? How difficult is the installation???

PS: I only hear sound and not picture from the last 2 links although it all works fine when I try the links from my phone. Let me know if they don't work.

Thanks,
Mark

[scarceller]

You mentioned that it's idling at 1000RPMs, this is wrong. The early cars 84-86 idled at 800RPMs while later 86-89 at 880RPMs. If it's idling at 1000RPMs it's a red flag that something is not correct. Often it's the idle switch not making contact.

The other thing that strikes me in those videos is how it almost seems like you're hitting a rev limiter at 5800RPMs. Are you sure the tach is accurate?

As for those hoses with cracks in them they all need to be replaced. Don't even bother smoke testing or any other air leak testing till you replace them. Any crack in those oil breather hoses is bad.

[scarceller]

I just watched the video again and in your 2nd gear runs the tach is accurate. In the stock 3.2L 2nd gear at 60MPH is right around 5800RPMs I can clearly see your tach and speedo match up. So I'd say the tach is accurate for that run.

WARNING PLEASE READ: Stop pulling WOT runs! You have no idea what your mixture is at at WOT, if you really have a air leak and the mixture leans more than >13.5AFR you are in very dangerous territory. You know something is wrong do not push that motor that hard any longer. You really need to find out what your mixture is at.

What about the O2 sensor, have you unplugged it yet? If not please do so now and see if anything changes.

[Dubbin']

Originally Posted by scarceller

I just watched the video again and in your 2nd gear runs the tach is accurate. In the stock 3.2L 2nd gear at 60MPH is right around 5800RPMs I can clearly see your tach and speedo match up. So I'd say the tach is accurate for that run.

WARNING PLEASE READ: Stop pulling WOT runs! You have no idea what your mixture is at at WOT, if you really have a air leak and the mixture leans more than >13.5AFR you are in very dangerous territory. You know something is wrong do not push that motor that hard any longer. You really need to find out what your mixture is at.

What about the O2 sensor, have you unplugged it yet? If not please do so now and see if anything changes.

I know... I'll stop... I hate this.... O2 is unplugged yes, did it when I re-installed black coil. I really pushed it to get it on video to show the hesitation - I stopped pushing it when it started hesitating a few months back. Did it when I re-installed black coil.

what should be my next step? check plugs? install a wideband?

Thanks,
Mark

[Dubbin']

Originally Posted by scarceller

You mentioned that it's idling at 1000RPMs, this is wrong. The early cars 84-86 idled at 800RPMs while later 86-89 at 880RPMs. If it's idling at 1000RPMs it's a red flag that something is not correct. Often it's the idle switch not making contact.

The other thing that strikes me in those videos is how it almost seems like you're hitting a rev limiter at 5800RPMs. Are you sure the tach is accurate?

As for those hoses with cracks in them they all need to be replaced. Don't even bother smoke testing or any other air leak testing till you replace them. Any crack in those oil breather hoses is bad.

Idle switch should be cleaned or replaced? Is there a proper way to test it?

Tach is about 10-15 KM/H fast - I've compared it to a GPS speedometer.

Thanks,
Mark

[cabmandone]

Originally Posted by scarceller

You mentioned that it's idling at 1000RPMs, this is wrong. The early cars 84-86 idled at 800RPMs while later 86-89 at 880RPMs. If it's idling at 1000RPMs it's a red flag that something is not correct. Often it's the idle switch not making contact.

The other thing that strikes me in those videos is how it almost seems like you're hitting a rev limiter at 5800RPMs. Are you sure the tach is accurate?

As for those hoses with cracks in them they all need to be replaced. Don't even bother smoke testing or any other air leak testing till you replace them. Any crack in those oil breather hoses is bad.

My thought exactly. He mentions and it shows 5600 and hesitation. Also agree that the hoses should go.

I can't hear the hesitation in your video clips but are you feeling the car stutter a little? It seems too balanced that it's popping at the same RPM. It's almost like someone moved the rev limiter back in the rpm range by about 600 rpm.

Are you hearing any popping in the exhaust? Normally if you're lean you'll also hear a "lean pop".

On the idle switch, you should be able to hear the switch click when you open the throttle.

[scarceller]

You really need to have AFR numbers at this point as they will tell us what's going on with fuel and AFR. We need to know if fuel mixture is causing this, if it's not mixture then it's ignition.

A really good decent permanent mount WBO2 gauge is the AEM gauges, decent price easy install. Something like this one:
Aem 30 4110 Digital Wideband Uego Controller Air Fuel Ratio Kit New Bosch 4 9LSU | eBay

To properly test the idle and WOT switches you just need a 12 volt test light or a volt meter. With test light you can test like this:
- With engine off and no key in the ignition
- Take the red lead from the test light and wire it to a fuse in the rear fuse panel, you just want 12 volts wired to the light's red lead.
- Pull back the rubber boots on both the WOT and Idle switch so that you can access the 2 pins for each switch from the back of the connectors. You want to leave the harness connected to the switches but be able to access the pins from the back side. To do this the rubber boots need to be pulled back off the harness.
- Now take the '-' lead from the light and touch both terminals at the back of the idle switch. If the idle switch is close and at idle both terminals MUST light the light.
- Now open the throttle so you come off idle, when you do this one of the 2 terminals will cause the light to go out. Meaning, one terminal always has the light lit no matter if the switch is open or closed (this is the ground side of the switch). The other terminal is the signal side of the switch and this terminal goes to the DME. This other terminal is the one that goes from light lit at idle to light not lit if you come off idle.

Then the WOT switch is similar in that it also has 1 terminal that's the ground terminal and will always have the light lit. The other terminal will light the light as the throttle reaches about 80% or more. With the WOT switch you are looking for the light to be out at less than 80% throttle and then the light comes on at more than 80%.

You can also test the switches with a ohm meter with them unplugged but that does not fully test the switches ground terminal nor does it test the switch in an active state. I always test them connected with my procedure above.

You can't clean the idle switch it's a sealed unit, if it's bad it needs replacing. The WOT switch can be opened up and then the contacts can be cleaned, often the WOT switch has corroded contacts since it sees little use.

Test both of the switches.

[scarceller]

One more thing: can you please take pictures of the inside of the cap and the rotor so we can see them? Also the inside of the distributor with the cap and rotor removed.

Have you tried spraying water around the wires while at idle? You need to keep in mind that the 5400-5800RPM area is the peak torque area for these motors and if an ignition component is at issue it's likely to fail at those RPMs. Spark plug gaps need to be at 0.7mm and no larger. I also recommended looking at the wires and ignition system in the dead of night with the engine at idle to see if you can spot any arcing. A spray bottle full of water can be used to spray at and around the wires to see if that yields signs of arcing.

But it's also important to rule mixture issues out first, I always rule out mixture issues first since that's easily done with a WBO2.

[Dubbin']

Originally Posted by cabmando

My thought exactly. He mentions and it shows 5600 and hesitation. Also agree that the hoses should go.

I can't hear the hesitation in your video clips but are you feeling the car stutter a little? It seems too balanced that it's popping at the same RPM. It's almost like someone moved the rev limiter back in the rpm range by about 600 rpm.

Are you hearing any popping in the exhaust? Normally if you're lean you'll also hear a "lean pop".

On the idle switch, you should be able to hear the switch click when you open the throttle.

I agree it's hard to see in the video. It's like if the engine cuts out... As Sal mentioned it almost feels like a Rev limiter.... It obviously scares/surprises and I let off the gas which is why it's hard to see in the videos. If you can get the volume high enough you will hear it. I only let off the gas once it hesitates thus the initial lack of power is unintentional...

No popping/backfires or anything out of the ordinary from exhaust.

I will try and listen for the ICV click. That will require someone to help me out.

Thanks a lot!!!
Mark