Mysterious intermittent lurching

[The Pinkfingers]

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.

[jessef]

How is the IP on it ?

Your symptoms sound like a fuel delivery issue.

[CVI]

Hi Pinkfingers,

I'm sorry I missed you this morning. But I have another possibility of what the problem might be. How's your idle speed going? Is it consistently at 750rpm or more? What is the rpm at cold early morning start compared to a warm engine start up? The reason I'm asking is because the cold start valve might be sticking and your rpms might be too high (over 1000 rpm) than the specified idle rpm. And when it's that high and you shift your gear to drive, it will definitely jerk up. Your delica is the newest model if I remembered right and you have the automatic choke system where the coolant is connected to your automatic choke which supposedly should maintain the idle at 750rpms.

Check what your idle is at park and neutral and should always be in the 750to 800rpm mark. If that's the issue, we may need to check the auto choke feature of the injection pump and see what's wrong.

Just advise.

mitsubc
CVI Automotive

[mriguy]

by no means do i claim to be a mechanic, but it sounds vaguely familiar to a "throttle position sensor" problem i once had where the engine would race and then settle down as well as lurch my vehicle forward before finding it's gear as well...just a potential lead...does the engine ever just rev up for no reason when idling, and then settle in at 750 ish?

[DelicaMark]

Hey mriguy that is exactly what my van is doing. Where and what is the "throttle position sensor". The idling thing has been happening to my ride over the last 6 months.

-Mark

[mriguy]

hmmmmm.....so i'm new to the deli and it's mechanics, so i might need confirmation from a "real" mechanic, but a quick search reveals this:

http://www.delica.ca/forum/injection-pu ... ion+sensor

and here's what it does in essence (prob. holds true for our beloved deli):http://en.wikipedia.org/wiki/Throttle_position_sensor

now, ususally it will act as if the accelerator gets stuck, but it's usually a computer (ECU) misread, in which case the replacing the TPS should be the simplest fix i think, but i don't think it would be that big of a job...definitely need some pro. help here though...

sorry to jack the thread...

[The Pinkfingers]

Hadn't thought of fuel delivery... was focused on the tranny. Regarding fuel delivery, I know it's not the injectors, as I had the CVI Deli tune done (ultrasonic injector cleaning). As for the IP, it was part of the 75 point inspection that Japanoid did, and they checked it off as functioning OK with no leaks, but that's all I know about it.

Hi Pinkfingers,

I'm sorry I missed you this morning. But I have another possibility of what the problem might be. How's your idle speed going? Is it consistently at 750rpm or more? What is the rpm at cold early morning start compared to a warm engine start up? The reason I'm asking is because the cold start valve might be sticking and your rpms might be too high (over 1000 rpm) than the specified idle rpm. And when it's that high and you shift your gear to drive, it will definitely jerk up. Your delica is the newest model if I remembered right and you have the automatic choke system where the coolant is connected to your automatic choke which supposedly should maintain the idle at 750rpms.

Check what your idle is at park and neutral and should always be in the 750to 800rpm mark. If that's the issue, we may need to check the auto choke feature of the injection pump and see what's wrong.

Just advise.

mitsubc
CVI Automotive

Now this is interesting. When we first got the van, the idle rpms were really high. Cold starts were OK, about 700-750 rpms. Once warm though - as high as 1300 rpms in park, and around 750-800 in drive. (This was getting worse, as it used to idle in park at about 900-1150 when warm). I took it to Japanoid, and they adjusted the rpms. It was fine after that, though occasionally when I put a semi-warm engine in park it would rev up to 900-1000. However, lately the idles have been really low - around 500-550 cold start, 700 warm. It just started doing that one day.

We are leaving to Sorrento on Monday, so over the next week I'll keep an eye on these things, and if it lurches I will note what the rpms are doing. I just want the problem diagnosed!! Thanks for everyone's input so far. Hopefully the mystery will be solved soon for the betterment of Delica owners everywhere...

[jessef]

As for the IP, it was part of the 75 point inspection that Japanoid did, and they checked it off as functioning OK with no leaks, but that's all I know about it.

So was mine.

Visual inspection of the IP/seals won't determine whether the solenoid or internal linkage maybe 'off' or not functioning inside the IP.

I remember when I first saw your Delica (idle speed vs. neutral vs. in gear being all over the place).

I'm still leaning towards issues with the IP.

Inspection/delica tune/injector cleaning didn't solve my lurching/smoke issue. I had to have the IP rebuilt.

Good luck & let us know how it goes.

[BCDelica]

There is a file, L300-fuel injection systems.pdf, available on the Wiki that may offer some troubleshooting tips.

[CVI]

As jerking or "jack rabbit starting" of the delica is bad for the tranny (it would eventually burn the clutches out as there's a lot of parts stressed out when the van jerks forward or backward considering the weight of the delica...pulling over 2000kgs of weight abrubtly), you always would want to shift it to drive or reverse with the idle at 800 or under for a smooth transition.

Comparing this scenario to a gasoline car is like starting to release the clutch at first gear or reverse at 1200 rpm abrubtly...what happens....doesn't it lurch forward??

Just a thought.

mitsubc

[The Pinkfingers]

If it were a fuel pump issue, why would a tranny flush help? The first flush helped immensely, but not permanently.

[Green1]

one thing some people have reported is that if the air conditioning is on, when the compressor kicks in the revs jump substantially, this can cause the van to surge forward if you're not careful...

[delicat]

Very true Green1 but also very easy to adjust... (see previous post from mitsubc). We did mine and the rev while on AC are now going up by only 50-75rpm and don't have the lurching anymore.

[The Pinkfingers]

one thing some people have reported is that if the air conditioning is on, when the compressor kicks in the revs jump substantially, this can cause the van to surge forward if you're not careful...

I wish it were this simple, but we haven't turned on the air conditioning yet. So it can't be that.

[The Pinkfingers]

Dropped off the Jammy Dodger at Japanoid today. They were going to swap trannies with a used one they brought in from Japan, but were a little unsure about the fact that mine is a 1994.

So they are sending the transmission to a specialist shop for them to overhaul. Looking forward to everything working properly.

In the meantime, David from Japanoid lent us his own personal Pajero to drive for the week our van is in the shop. Have to say that was mighty kind.