Another low power/hesitation thread

[wolfwagon]

Hello! I have lurked the samba for a couple years now and figure it's time for a post since I am no longer making progress trying to unfark my van.
I have a 1984 Vanagon with a 2.1 block and 1.9 system. I have been having several problems over the last several months especially a hesitation problem requiring matting the pedal to the floor to move from a stop. The van responds with adequate power when floored but any thing less will result in a crawl from a stop accompanied by puttering and sputtering. This problem becomes very obvious as the van warms up. Usually not obvious when cold. Timing has been set according to tencentlife's method, around 38 degrees when all in. Still runs poopy, better when the timing is more advanced beyond current setting.
Oxygen sensor has been mysteriously routed through a relay that is same model as the fuel pump relay (the ones in the little box above coil). Not sure what to make of or do with that set up...Maybe this is contributing to the problem.
Van also runs hot after warm up, has clicked/tapped/lifter noise since purchase 2+ years ago, and finally my oil pressure sucks. Like 4 psi at idle sucks, red light on, 20 psi at highway speeds.
Vacuum testing shows a rapidly bouncing needle on gauge at idle (valve or guide problems?)
Are my problems possibly related to an engine on it's way out? Any more info I can provide to be of more help? Thank you for any input

[atomatom]

first; has your van always been like this? or just recently?

on the oil pressure thing, what oil/filter are you using? that is one easy fix. otherwise, could be oil pressure relief valve spring (cheap, also easy!), or, perhaps the dreaded expensive thing, dem bearings, or perhaps a bit easier, a worn oil pump (or one installed poorly).

may the farce be with you.
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[wolfwagon]

Only recently has the hesitation become extremely annoying. Since moving to Pacific NW 7 months ago. Didn't run hot until I replaced thermostat, but then again the old one was stuck open.
Oil has been 20w/50 with a Mann filter since owned and a quart of Marvel Mystery Oil last two changes. I think the MMO is making it too thin. Engine according to paperwork was allegedly done by Boston Bob and has about 25,000 miles on it, so I'm hoping it's not the bearings. Oil pump or spring are likely candidates to check tomorrow.
Thank you for the input!

[atomatom]

hot oil will make for low pressure, so i think the first thing you need to address is that. apparently, quite a few thermostats are either bad or the wrong type.

one upgrade for engine longevity is an oil cooler kit. this is on my wish list: http://www.vanistan.com/oil_cooler_kits.html
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[atomatom]

the oxygen sensor setup sounds very strange too though, so, that could also be a problem. many people have issues with bad grounds or cracked wires, both of which are easy things to check with a multi-meter and easy enough to fix.

the digijet pro training manual gives a lots of detail on how to diagnose which part of the electronic fuel injection is wonky. http://www.vanagonauts.com/files/Digijet_FI.pdf
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[wolfwagon]

Oil pressure is better with no oil and no MMO, still low after highway runs but now I have about 6 psi at idle with red light on. Changed some tune up items as well and now the van runs extra well cold, crappy throttle response once warm, but running cooler.
I do not like that oxygen sensor set up one bit, got a new one today, going to try to figure how it was supposed to be wired originally and install it after the rain/hail quits. Thanks for all the tips and links, time to just check the whole electrical system again. Seems like pin tests at the ecu and wiring inspections are becoming a monthly maintenance item. I'm much past do to print out the pro training manual anyway.

[atomatom]

btw, i believe the reason you get a good response when you floor it is because that triggers the throttle switch that says "to be damned with your optimizations computer, full speed ahead" and then ignores the ECU, which seems to be acting wonky, be it from a sensor error or what not.
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[atomatom]

also, for reference, when hot, my van (84) idles at 15-20 PSI (50-60 cold). but i just rebuilt it, new bearings, oil pump, spring, bla bla bla. similar PSI when running 20/50 or a 5/50 synthetic.
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[Howesight]

MMO is only meant to be used in the engine oil at oil change time and only for a very limited period of running. You can put it in your gasoline any time. It makes crankcase oil so thin that oil pressure drops - - not good.

On oxygen sensors, as long as there is not a grounding short in the signal wire from the oxygen sensor, the Lambda system is the saving grace of both the Digijet and Digifant EFI systems, masking problems like leaking throttle bodies, worn out AFM, small vacuum leaks etc etc.

If you have a moderate to large vacuum leak, the Lambda system can make things worse. The bottom line is that the WBX EFI systems are not sophisticated and cannot compensate for things like:

1. Vacuum leaks such as:
- failed PCV diaphragm (really just another form of vacuum leak);
- worn throttle shaft;
- leaking intake runner hoses;
- hardened and leaking fuel injector O-rings;
- cracked rubber boot (air filter to throttle body);
- brake booster vacuum leak;
2. Aged cap, rotor, plug wires, plugs;
3. dirty injectors that squirt instead of atomize fuel;
4. Exhaust system leaks (skews oxygen sensor output);
5. Corrosion in terminals or wires between sensors and the ECU and/or ground. You test for corrosion by ohm-testing the circuit, not just by visual inspection of the wire or terminal. This goes double for Vanagons in the salt belt.

Since your engine is a hybrid, make sure that you have the correct distributor for the 1.9 WBX (it should have a vacuum canister) and that the timing is correctly set and the advance mechanism in the distributor is mechanically sound (ie: moving the advance plate when vacuum is applied).
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'86 Syncro Westy SVX

[morymob]

Try unplugging oxy sensor, test-any change? None, unplug temp 2 sensor, test also, change?? The 'mule' my syncro did this a couple wks ago, was plug connections of temp 2 sensor.

[wolfwagon]

So I spent yesterday massaging the wiring harness, looking for bad connections and cleaning grounds. Replaced all vacuum hoses and t's. My oddly wired oxygen sensor looked as though it wasn't wired in any way that would cause it to operate correctly anyway so I disconnected it.
Yes atomatom that pretty much describes my feelings about it as well "to be damned with your optimizations computer, full speed ahead"! At least the Throttle Switch gets it.
I had read some posts by TerryK that recommended MMO with every change but I don't think that method is for me and my van. Thanks Howesight.
I adjusted the timing until the hesitation seemed to go away and drove it around. With the timing set as it is now right at 5 degrees BTDC at idle but nearly 47 degrees all in. I have good operating temps and much better performance but I still get the occasional bog/lag.
When preforming the pin out tests at the ecu (Bently 24.20) however I cannot get a voltage reading when trying to test the Hall sensor, I believe I am supposed to be getting battery voltage or slightly less? Also resistance when testing fuel injectors is closer to 18-19 ohms instead of the recommended 16-16.4 ohms. Where to go from here, then?
At least Bessie Lou is running a little better and accelerates a little better but I believe I am only masking bigger problems with her. Thank you everyone for your helpful suggestions so far!

[Ahwahnee]

wolfwagon wrote:

...With the timing set as it is now right at 5 degrees BTDC at idle but nearly 47 degrees all in...

Of course 'by the book' the Digijet wants 5° ATDC at idle. In addition, I would be wary of advance higher than 40°.

With what has gone before (that relay and who knows what else) I can see how disconnecting the O2 might help for now but for ideal operation you will want it correctly connected.

[GWTWTLW]

I have been experiencing something similar. I believe mine is directly affected by my exhaust. Until recently, I have had pretty bad exhaust leaks. When leaking, I had no issues with lag off idle. When I would temporarily patch, I would notice the sluggishness. Now with my exhaust permanently fixed, I am noticing it regularly. I believe I was running rich with the leaks which masked the issue. My timing was pretty retarded which I thought was probably the issue but it is adjusted properly now. My AFM is pretty new and I don't believe it is the TPS. I had the O2 replaced with the new exhaust. I haven't tried disconnecting it but it feels like it is working properly.

Any thoughts?

Thx!
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89 Syncro Westy - GW 2.5, now with a double knob job
@gwtwtlw

[wolfwagon]

Ahwahnee I meant 5 degrees ATDC. little V notch to the right of dish shaped TDC mark aligns with case seam at idle.
When testing the ECU's ground I have 2.4 ohms which steadily falls to 1.4 ohms instead of the recommended 0 ohms. I am assuming my ecu is not grounded properly. Or possibly my ecu is bad internally? anybody have a good one I can try in PDX area?
Also these were helpful in checking hesitation problems
http://www.thesamba.com/vw/forum/viewtopic.php?t=3...49807e93ab
http://www.thesamba.com/vw/forum/viewtopic.php?t=409221
also attach a vacuum gauge to your system and use this to diagnose it
http://www.flatheadv8.org/vacuum.jpg

[wolfwagon]

So if one had a 3 wire oxygen sensor and only the sensor wire had a proper connection to the fuel injection system where would the other 2 wires be wired into the system for proper operation?

[Ahwahnee]

[Uncle Andy]

I am also having this issue. Horrible hesitation off idle with generally poor performance overall. In my case, unplugging the O2 sensor improves the situation. Of course, then it runs super rich and the gas mileage is abysmal. Things that I have tried (to no avail):

New O2 sensor
New Temp II
Cleaned and checked AFM (perfectly good)
Checked vacuum leaks (none noted)
Replaced throttle body
Adjusted timing
Replaced cap/rotor
Replaced vacuum advance unit
Tried different coil

My next steps are replacing the Ignition control unit and the Hall generator. And trying to swap the ECU for a spare, but the spare is an unknown, pulled from a junker.

Please let me know if you solve this issue.

[Uncle Andy]

Update and beg for mercy:

I have now swapped distributors, as well as done all checks on the hall unit/ignition control module/coil. I have also checked the fuel pressure and the pressure regulator, plenty of fuel getting through. I have also swapped the ECU.

Still the horrible hesitation continues.

Anyone located in the Knoxville, TN area have a working 1.9 AFM that they will let me swap out for a few minutes? I'm grasping at straws here.

[65Tops]

Go back to the basics:
Check compression, Vacuum @ Idle, and do a Leak-Down test.
I had the same issue and I was scratching my head for months. I had only 13 in vacuum at idle. There was just enough Blow-By that the vacuum was affected. The rings were shot. Vacuum can also be affected because of leaking valves. Without good vacuum the air flow meter can actually close to its stop when snapping the throttle because the engine is using the crankcase gasses, not the metered air through the AFM. This throws off the whole load calculation in the ECU which controls timing advance and fuel delivery. The ECU thinks there is less load then there really is. As RPM's increase (say above 2500) this diminishes. Putting your foot to the floor Wide Open Throttle the ECU somewhat ignores the AFM input due to the Throttle Switch. If you could monitor the exhaust gasses during the hesitation (say with a wide band O2 monitor) you would see that the engine is going lean. Try disconnecting the PCV hose at the air boot and plug the hole in the air boot. If you have a lot of blow-by you'll feel it coming out of the PCV hose attached to the breather tower. Try driving it this way around the block and see if your hesitation improves a bit. If so your prob. looking at a mechanical issue (rings, Valves etc.) A temporary fix that will help but not completely solve the Lower RPM-High Load hesitation is to relax the spring tension on the AFM Cog Wheel (as discussed in another topic). This however is just a Band-Aid. Unplugging the O2 sensor puts the ECU in a default state, richens the fuel mixture, and uses a map already stored in its memory, therefore somewhat compensating for that un-metered air. Fixing other problems like a bad connection at the coolant temp sensor or replacing a bad O2 sensor actually makes the hesitation worse because now the ECU is basing its calculations off correct readings instead of incorrect (richening) readings that were masking the hesitation.
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89 Vanagon 2.1 WBX Westy Camper "Spanky"

[morymob]

Haven't read anywhere yet but have you actually driven to test the oxy sensor being unplugged?? If u think tps sw flaky u can also unplug it, idle will fluctuate some but will run norm (not the wide open throttle ) 4 testing purposes. I have driven 2 or maybe 3 of mine temp/testing with oxy unplugged, still ran ok u only get a very slight fuel enrichment this way. Running a 2.1 with 1.9 accessories u should run normally, mine does. Have u tested fuel press, make cheap texter with dial tire guage, unscrew end & clamp piece of fuel hose on,clamp to 'T', keep in tool box. Remmove s hose from afm, move inside flap,make sure it'snot sticky moving from home poposition, at this time u can also conn meter on plug terms , move flap should get smooth resistance change.