Mysterious intermittent lurching
Posted: Fri Aug 01, 2008 6:39 pm
This is weird, and no one can diagnose the problem.
We noticed soon after we got it that when we were slowing down and almost at a full stop, or when we were first accelerating from a full stop, that the vehicle would begin to lurch. This problem was increasing, and even when we were at a full stop, and took our foot off the brake to idle forward (for example, while waiting at a traffic light), the vehicle continued to jerk forward (rather than coast forward).
Also, sometimes when starting from a full stop, the engine would rev for about half a second and then suddenly connect ("find it's gear"), lurch, and start moving. I should note that this seems to happen when the engine is warm, but not when we first start out in the morning.
I fear it may be the transmission, because this issue happens when we are in Drive or 2nd gear (almost like it can't make it's mind up as to what gear it needs to be in). However, if I gear down when stopping, and then start from Low gear, there is no lurching when stopping or starting or idling forward.
It does not happen all the time, but once in a while. Before we took it in the first time, it was a couple times a day.
It's still under warranty, so I took it to Japanoid. They did a tranny flush and adjusted the cable. It was great for a week, then a week later... lurch lurch. Fine for another week, then again... lurch, lurch.
Took it back to Japanoid, they couldn't figure out the problem so took it to the tranny shop they use. The tranny shop's best guess was forward clutch pack seal was leaking, which causes the the clutch to engage and release at low idle speed (because low oil pressure). They said a tranny rebuild was needed. Japanoid wasn't convinced or happy at that news.
Wanted a second opinion, so called Butch at CVI, he said the forward clutch pack seal didn't make sense, because that would cause it to lurch all the time. He thought it might be a piston or valve that occasionally sticks, especially if there's crud built up on the tranny. He said he would keep flushing the tranny a few times to see if that helped.
So took it back to Japanoid again today - this time they did a tranny flush and replaced the filter and rubber gaskets. Half way home, guess what... lurch, lurch.
So... could it be a sticky piston and perhaps it lurched today because it takes a while for the new tranny oil to get to all the nooks and crannies?
Could it be a leak in the forward clutch pack seal?
Could it be something else unrelated to the tranny?
Could it be so unknown because it has something to do with the fact that there are a few different features on a '94 engine?
This is a big stretch, but I'm wondering if it could be connected to the thermostat (because it happens when the engine is warm). I wonder because Butch said at the CVI Deli Day that engine temp should hover just below the half way mark of the temperature gauge. He also said if the thermostat goes, it has a fail safe that keeps it open all the time (so you don't overheat). And in the Jammy Dodger, our temperature is usually between the 1/4 to 1/3 mark and I've never seen it hit 1/2. This may be because '94s have a cold start valve, but I'm wondering if the thermostat is blown, and could that at all make the van lurch. I know, I know, a real long shot.
Has anyone had this problem before? James at Japanoid has never seen it happen before. Everyone seems to be mystified.
We noticed soon after we got it that when we were slowing down and almost at a full stop, or when we were first accelerating from a full stop, that the vehicle would begin to lurch. This problem was increasing, and even when we were at a full stop, and took our foot off the brake to idle forward (for example, while waiting at a traffic light), the vehicle continued to jerk forward (rather than coast forward).
Also, sometimes when starting from a full stop, the engine would rev for about half a second and then suddenly connect ("find it's gear"), lurch, and start moving. I should note that this seems to happen when the engine is warm, but not when we first start out in the morning.
I fear it may be the transmission, because this issue happens when we are in Drive or 2nd gear (almost like it can't make it's mind up as to what gear it needs to be in). However, if I gear down when stopping, and then start from Low gear, there is no lurching when stopping or starting or idling forward.
It does not happen all the time, but once in a while. Before we took it in the first time, it was a couple times a day.
It's still under warranty, so I took it to Japanoid. They did a tranny flush and adjusted the cable. It was great for a week, then a week later... lurch lurch. Fine for another week, then again... lurch, lurch.
Took it back to Japanoid, they couldn't figure out the problem so took it to the tranny shop they use. The tranny shop's best guess was forward clutch pack seal was leaking, which causes the the clutch to engage and release at low idle speed (because low oil pressure). They said a tranny rebuild was needed. Japanoid wasn't convinced or happy at that news.
Wanted a second opinion, so called Butch at CVI, he said the forward clutch pack seal didn't make sense, because that would cause it to lurch all the time. He thought it might be a piston or valve that occasionally sticks, especially if there's crud built up on the tranny. He said he would keep flushing the tranny a few times to see if that helped.
So took it back to Japanoid again today - this time they did a tranny flush and replaced the filter and rubber gaskets. Half way home, guess what... lurch, lurch.
So... could it be a sticky piston and perhaps it lurched today because it takes a while for the new tranny oil to get to all the nooks and crannies?
Could it be a leak in the forward clutch pack seal?
Could it be something else unrelated to the tranny?
Could it be so unknown because it has something to do with the fact that there are a few different features on a '94 engine?
This is a big stretch, but I'm wondering if it could be connected to the thermostat (because it happens when the engine is warm). I wonder because Butch said at the CVI Deli Day that engine temp should hover just below the half way mark of the temperature gauge. He also said if the thermostat goes, it has a fail safe that keeps it open all the time (so you don't overheat). And in the Jammy Dodger, our temperature is usually between the 1/4 to 1/3 mark and I've never seen it hit 1/2. This may be because '94s have a cold start valve, but I'm wondering if the thermostat is blown, and could that at all make the van lurch. I know, I know, a real long shot.
Has anyone had this problem before? James at Japanoid has never seen it happen before. Everyone seems to be mystified.