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Engine problems,not idling cold,hesitates if floored(im new)
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SockMonkey
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PostPosted: Thu Nov 13, 2008 1:22 pm    Post subject: Engine problems,not idling cold,hesitates if floored(im new) Reply with quote

Ok, I am new to vanagons, have owned mine for a couple months, its a 1985 1.9L GL. If I start it COLD it will NOT run it starts then dies almost immediately. If I start it and floor it, it hesitates and takes probably 3 times longer to red line.. but if I floor it a couple times the hesitation will go away, like its cleared out. But if you just start it and floor it a couple times and just take your foot off the gas it will still stall. But if you hold it at like 2-3k for a little bit it will idle... Once its warmed up it will idle fine at stop lights and so on. Also only getting about 14mpg, with new O2 sensor.

My dad (who was a mechanic for like 20 someodd years) would hold the throttle at about 2-3k (while warmed up) and move the AFM with his finger and it would rev up about 500rpm (guessing) and seem to be smoother.

My question is, could a bad AFM cause what I described? Any other thoughts? how much is a AFM? should I buy new or try and find one at a junk yard? (local one has a few vanagons).

Thanks, Silas.
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0to60in6min
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PostPosted: Thu Nov 13, 2008 2:07 pm    Post subject: Reply with quote

look at this

http://www.thesamba.com/vw/forum/viewtopic.php?t=324909

may be you get something in there....

good luck
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Dogpilot
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PostPosted: Thu Nov 13, 2008 2:22 pm    Post subject: Reply with quote

The big thing that is indicated is the flooring it a few times seems to clear it out. As it cools down in the Northern Hemisphere a lot of the stuff acts differently. The throttle has two switches on the pre-86 vans, one for idle and one for wide open. If the low end switch is sticking, which they do in the cold, it may be due for replacement. The low end switch makes the engine think it must idle. The micro-switches used in the Van are not of the highest quality and as they age they get sticky. Frequently the little plastic cap put on it to keep water out gets less flexible, so it may keep the switch depressed, or the internal mechanism may go bad. I would check this switch first and then troubleshoot from there if it is not it.
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SockMonkey
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PostPosted: Thu Nov 13, 2008 2:30 pm    Post subject: Reply with quote

For the 2-3 months I have owned it I have never noticed any hiccuping or hesitation once its warmed up or has idled for 5-6 minutes. The only hesitation I ever noticed is when I start it up (at 20-25 degrees out) and take off, then it would hesitate as I accelerated but I would let it get to 5k in first gear and after that no more hesitation. The problem got progressively worse as it got colder and colder in the morning, past couple weeks have been frosty up here. I have been starting it before I get in the shower, then leave right when I get out, (about 15 minutes) when I do this I notice no stalling hesitation (never had hiccups or hesitation while driving). The only problem that stays once warmed up is bad mileage and rich smelling exhaust.

as I mentioned when we held the throttle at about 2-3K then played with the AFM it seemed like we could get 500rpm more out of the same amount of throttle. which leads me to think AFM.
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Dogpilot
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PostPosted: Thu Nov 13, 2008 2:37 pm    Post subject: Reply with quote

The switch is overridden by the ECU when the RPM's go over 3K. The other culprit can be the Temp II Coolant Temp Sensor. It and the O2 make the engine go very rich. Check the switch first, start with the $20 items and work your way up to the $350 later. The AFM is all too often blamed for bad sensors, switches and bad adjustments.
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SockMonkey
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PostPosted: Thu Nov 13, 2008 2:44 pm    Post subject: Reply with quote

hehe alright... I did notice that, $275 plus like $75 core for Bosch AFM.... at that price I woul dbe paying a visit to local junk yard and buy all they had. and swapping them out one after the other. There was one for $170. But how would the switch affect it only when the engine is cold? You said it makes it think it must idle, well it doesnt idle... if I start it and take my foot off the gas (which I must use to get it started) then it just stalls, and then its even harder to get it to start again. But once its floored a couple times it seem to idle, bearly... but once its warmed it idles fine. And when it hesitates, it hesitates in a couple locations on its way up, I think Razz I will have to check.

OHH, I think I know what your saying. If the switch sticks when you floor it, it tells the engien to idle instead of reving up, then unsticks and allows the engine to rev? But it still sucks at idling when I just start it up cold...


Last edited by SockMonkey on Thu Nov 13, 2008 2:51 pm; edited 1 time in total
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madspaniard
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PostPosted: Thu Nov 13, 2008 2:50 pm    Post subject: Reply with quote

I have similar problems, check the link below

http://www.thesamba.com/vw/forum/viewtopic.php?t=327481

in bed recovering from surgery so haven't had time to check this but looks like throttle switch might be the culprit
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SockMonkey
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PostPosted: Thu Nov 13, 2008 2:54 pm    Post subject: Reply with quote

Probably a couple things together... The switch could be (propbably is) causing the hesitation when first starting. But other things (Temp II Coolant Temp Sensor) could be causing bad idle and running rich. (just replaced O2 sensor).
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Dogpilot
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PostPosted: Thu Nov 13, 2008 2:59 pm    Post subject: Reply with quote

The idle is one issue and the hang is another. Your idle is regulated by two things, your Idle Control and the bypass screw on the AFM. The 85 has a procedure where you bypass the Idle Control by plugging the two connectors that go into its black box to each other. Then the idle is set by adjusting the Bypass Screw.

This is all a waste of time if the Throttle Switch and the items like the Temp II are not doing their jobs correctly. The Temp II puts the engine in warmup (rich) mode while the coolant is below a preset level. Then when the level is reached it lets the ECU take over running normally. The O2 takes over regulating mixture after the engine is warm. The AFM is really a measure of the amount of air going in the engine, it uses the signal from the wiper and the Temp I sensor, located in the AFM to figure out how much air is going into the engine at any given temperature.
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98 Disco I
08 Range Rover SC
08 VW Rabbit S
1951 O-1G
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Captain Pike
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PostPosted: Thu Nov 13, 2008 3:33 pm    Post subject: Reply with quote

Bentley page :24.35 Second paragragh "note  
Correct ajustment is important. Following are conditions that are created by improper ajustment. 
Gap A to large
Engine surges with lean condititon  
Gap a too small
With cold engine, stalling at full throttle acceleretion.
With engine warm, no deceleration fuel shut-off.

Start on page 24.30 and perform all tests.[/i]
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