My mk2 1.8 has been stalling. Usually it's when I'm in town and have to stop quickly. I put in the clutch and the revs drop to zero. It always starts right back up. It doesn't happen all the time. Every once and awhile the revs drop to zero then it bounces up to 2500, then normal idle. It's a 90 with about 155000 miles. Otherwise runs strong and has a fairly recent timing belt, plugs, cap, etc. Can anyone point me in the right direction? Thanks!
Inspect each vacuum line and their connectors for signs of cracks/holes. Inspect the boot from the air filter box to the intake manifold for the same. enJoy enJoy
AND inspect the ground wires for the fuel injection that bolts to the intake manifold or cylinder head. Usually they break due to vibration.
A dirty Air Regulaor Valve (if the proper name) might do it too?
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And wear; as vibration makes some rub through the wall in the space of about 10 years of normal driving. Check the main vacuum tap on the end of the manifold and the plastic fittings (including check valve) for the brake servo and reservoir. One non-obvious place for the line to rub through is the hard line as it passes next to the battery on the way to the vacuum reservoir underneath the battery, behind the headlight.
Idle stabilizer valve.
Also make sure that the PCV valve grommet onto the cylinder head isn't leaking. A quick (albeit a little unreliable) check is to press down on the PCV valve while the engine idles and see if the idle fluctuates. If it does; there's a leak. If it doesn't, there still might be a leak -- hence the "unreliable" test comment but at least you don't have to unscrew anything to find one that fails the simple test.
Similarly; check the plastic top part of the dipstick tube by removing the dipstick at idle and then replacing it. If idle DOESN'T "wobble" when you do that, you should replace the pink/orange plastic bit that clips onto the top of the metal tube. Check the seal on the dipstick itself while you're at it.
Hi, Hey, I've got the same model year. In addition to all the things to check mentioned so far, check out:
- connections on the distributor. I had infrequent loss in power especially when under load starting out or climbing a hill. Pulling out and re-seating the connectors on the distributor terminals seemed to solve the problem. Many months later, no near stalling nor stumbling.
- How are your fuel pumps? If the transfer pump in your fuel tank is not working, your main pump may not generate enough pressure when your revs drop (alternator output drops) to keep your engine going.
- How is your front engine mount? Any freeplay if you rev the engine? A worn mount may allow the engine to move stressing vacuum lines and air bellows. This is related to vacuum and air leaks others have mentioned. Best to fix the leaks too.
- I infrequently change all the fabric wrapped rubber hoses linking the vacuum lines just to eliminate any vacuum issues. A couple feet of the tubing is all you need to cut 3-4" pieces to replace the existing hose.
Let us know what works for you. Good luck.
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