rough cold idle/start, coolant temp spikes, and surging idle

[prockhold]

'84 Vanagon GL Wolfsburg with 2.3 GoWesty engine

My van is having some trouble after a recent install of a new 2.3 GoWesty engine. Only 170 miles on the engine. I have poked around on the forums and would like to get some advice from you guys.

First things first: The holy trinity of major problems

1) Coolant temperature randomly spikes HOT and light blinks.
Almost always on startup, the coolant light will blink and the needle will pin to the top (hot), and stay there for a couple of minutes. Then, the coolant light will turn off and the needle will return to accurately read the appropriate temperature. This happens on and off while driving. There is no difference in how the engine runs when the gauge shows hot. The fans operate as they should if it's a hot day and I'm sitting still in traffic. When the problem is not occurring and I can read the temperature, it reads smack dab in the middle of the needle range of motion.

2) When it isn't warmed up, the engine will fire up and rev to about 1000 RPM before it will die about two seconds later. I can keep it running by blipping the throttle to keep the RPM's around 1000-2000. If I take my foot off the gas for more than a few seconds, though, it dies. Only after blipping the throttle and keeping it running for 3 to 5 minutes will it be warm enough to idle on its own. Even then it'll still sputter and almost die before catching itself. It takes a few minutes longer for it to idle without sputtering, but it does eventually get there.

3) Surging idle when cold AND when warm.

Other than these three problems, the van runs very well.

Things that have been checked:
-vacuum leak found and fixed, but it made no difference
-timing was checked
-spark plugs were checked
-coolant level is fine
-no coolant leaks

Things that I am going to check:

-temp II sensor
-Air flow meter track/arm
-Auxiliary air regulator valve
-clean or replace the water temp sensor
-look for corroded wiring or worn out wire insulation for the water temp sensor

Is there anything else I should check? Anybody have advice on what is the most likely culprit (i.e. what I should check FIRST before wasting my time)?

I may have follow on questions about how to test whether some of these problem areas are faulty or not. I'm a novice with mechanics, so it is possible that some of these procedures could be out of my skill level, but I'll try my darndest.

Thanks guys!

[Terry Kay]

This you can do for the coollant light issue.
Remove the coolant sensor in the top of the expansion tank, and using sn old toothbrush dipped in CLR clean it up.
Put it back into the top of the tank, problem solved.
If not, buy a new one.
Common happening the gauge pegging & the light blinking after you first start it.

The cold & warm running issue is more than likely the thottle positioning switches not working or out of adustment.
Hope that they are working.
They are no longer available.
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T.K.

[hdenter]

While you are checking the throttle position switch, make sure that the "S" boot is tight on both ends and there are no other large vacuum leaks. If those things don't solve anything, have a look at the hoses to the Aux Air Valve and maybe see if the AAV is working properly.

Hans
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[Ahwahnee]

[prockhold]

Focusing on the cold idle problem since that is more pressing.

The throttle valve did not need adjusting. It "clicked" at idle and full open. I did the test for the throttle valve switch according to the Bentley on page 24.33. When the throttle was in the idle position, I got zero ohms. When the throttle was in wide-open, I again got zero ohms. Anywhere in the middle, I got no connectivity. I think that means that I've found the culprit, correct? Bentley says that the resistance should be infinity when the throttle valve is full open. Or am I getting confused about what "throttle valve open" means?

Thanks!

[Terry Kay]

Throttle valve = Throttle body butterfly.

Throttle arm all the way open, all the way closed.

Then get a vacuum gauge on the back side of the throttle body.
It should be giving you a 0 reading on the gauge at idle if you think it's correctly set.

If not, you'll get the bucking, jerking you are reporting.
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T.K.

[prockhold]

[ohhorob]

[Terry Kay]

And what is the vacuum reading off the rear of the throttle body nipple at idle?
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T.K.

[prockhold]

The engine running problems are solved!

The culprit was the throttle body and the throttle body seal to the intake plenum. The TPS was really difficult to adjust correctly. I noticed that the TPS would sometimes not click "off" to return to idle. Turns out it was because the throttle plate shaft had worn out, which allowed the throttle plate to stick to the wall of the throttle body.

Compounding that was the problem with the gasket between the TB and the intake plenum: it wasn't there. So there was a massive vacuum leak. Don't know how the two different Vanagon-specialized mechanics I took it to missed that one. I found the vacuum leak using the propane method.

I put in a rebuilt TB and new TB gasket from GoWesty and presto! all running problems solved. Thanks all for guiding me in the right direction!

For the record of those whom are searching this topic for a solution to their own problems, here's a summary of all the symptoms that the TB and gasket fixed:

-Very high idle on cold start (2k-3k rpm). This would last for 3 minutes or so.
-Surging idle (surging from 600-1100 rpm) very rapidly
-Stalling or sputtering when cold
-Bucking under light throttle (probably because TPS was impossible to adjust correctly)
-Rough and sudden idle shut-off while driving
-Throttle sometimes did not return to idle after taking foot off the gas pedal when it was hot outside AND the engine was cold. Once the engine warmed up it would always return to idle. My guess is that the warm weather expanded the TB components and made the plate stick.
-Van always drove perfectly fine under load

[johnbyrdgates]

I have a similar issue with my 87 2.2L Vanistan engine installation. I replaced the throttle body with a Rocky Jennings rebuilt before the engine swap. After the swap, the van ran great for 1000 miles and the began "missing" - running out of power in all gears at all speeds. It was still driveable, but like a 2-cylinder for power, which was disconcerting considering the newness of the engine.
Everything else checked out good and I thought I was having an intermittent wiring issue, since the original harness was reused. It occurred to me that the rebuilt throttle body was bored to 52 mm and that even the new throttle body gasket that I installed at engine swap wasn't sufficient to seal it once the motor warmed up.
A 2" pop up drain gasket from a plumbing supply company fits the gasket space and has more cushion than the flimsy and difficult to find gasket. A little loctite on the two screws holding the throttle body to the engine is a good idea, too.
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1987 2.1L 2WD Full Camper Kerouac

[amwaj]

i had the spiking temp gauge and light syndrome, bled, bled and re-bled the cooling system parked on a hill...that cleared that symptom up
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the best way to make a small fortune in life, is to start with a big one, and become afflicted with Vanagon-itis