4wd help!!
01-03-2018, 09:18 PM
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4wd help!!
No idea what is going on. In 2wd my truck runs great. I have a 95 4runner with 3.0. As soon as I put it in 4wd and start to accelerate it starts jumping all over the place like someone is cutting the fuel. Surging bucking all over. As soon as I let off the gas it coasts totally fine. There are a bit of issues that I would have thought this was accept that in 2wd the vehicle runs super smooth. Could this be EGR valve related?? Two days ago my 4wd was fine. Any help or brainstorming would be great. Have tried other forums with no responses. Thanks !!!
01-04-2018, 06:27 AM
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This is in the snow or dirt or any conditions. I do have ADD. Checked the vacuum lines to the actuator seem ok. It stays in 4wd just bucks like crazy throughout the entire rpm range. Worked fine a few days ago. Thanks for the input.
01-04-2018, 08:24 AM
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If the truck is running fine in two wheel drive and no issues, I suspect it is binding when 4 wheel is engaged. All four tires the same size? Having the correct tire size makes a big difference. Even having the correct tire size but two different brands can make a bucking/growling issue. Different brands are not always the same size. For example you may wear a 9 1/2 Nike shoe but a 10 in a Converse shoe. Check your tire size and brand and all match.
01-04-2018, 08:07 PM
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If the truck is running fine in two wheel drive and no issues, I suspect it is binding when 4 wheel is engaged. All four tires the same size? Having the correct tire size makes a big difference. Even having the correct tire size but two different brands can make a bucking/growling issue. Different brands are not always the same size. For example you may wear a 9 1/2 Nike shoe but a 10 in a Converse shoe. Check your tire size and brand and all match.
All same tires. It’s not so much of a bucking from grinding or chirping tires so to speak it’s only when applying the throttle. I can make some spread and take off the gas and coast and it does not lurch. I can also throw into neutral and coast with all 4 engaged and it’s totally smooth. I would assume that if there was something up with tires or diff or tcase that I would feel it in all these scenarios. I am stumped. I am prop going to replace all the vacuum lines and double make sure that they are hooked up correctly. If it were a vacuum line that was not add related do you think this could create my issue?
01-04-2018, 09:27 PM
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Ok. I might have found something. I noticed that my vsv for my ADD has only one hose running into the wheel well to the vacuum canister. The nipple on the bottom going into the wheel well has no hose. Not sure where this hooks up to the vsv or the canister but I will look farther. I’m curious as to if this could cause my condition as I feel the add is functioning now and 4wd light stays on through the hole lurching around.
01-04-2018, 09:35 PM
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Ok. I might have found something. I noticed that my vsv for my ADD has only one hose running into the wheel well to the vacuum canister. The nipple on the bottom going into the wheel well has no hose. Not sure where this hooks up to the vsv or the canister but I will look farther. I’m curious as to if this could cause my condition as I feel the add is functioning now and 4wd light stays on through the hole lurching around.
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01-04-2018, 11:12 PM
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It has to be some place in the ADD system other wise it would happen all the time.
Do you have a volt meter if the ADD system is pulling the voltage down it can make the engine miss and sputter
Not as likely as a Short should cause the circuit protection to open
Do you have a volt meter if the ADD system is pulling the voltage down it can make the engine miss and sputter
Not as likely as a Short should cause the circuit protection to open
01-05-2018, 06:56 AM
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I’m sure I can get my hands on one. Stupid question but where would I check the voltage? I do notice that shifting into 4hi my rpms drop but assume this is just the engine trying to pull vacuum. I was thinking about doing the ADD delete if I can’t figure it out. How much strain would that put on my front cv’s. Def a noob at a lot of this but I can follow directions. Just finished replacing my valve cover gaskets and replaced everything in my IFS. Now I just need to figure out this 4wd.
01-05-2018, 09:43 AM
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If you have a missing vacuum hose that could be upsetting the engine when the VSV switches to that open port. Try capping that port and see what happens. Your ADD could be stuck permanently in gear (the green light would still switch on/off with the transfer case position). You can check the ADD by putting the vehicle in 2wd with the engine running, and then shutting it off and crawling under it and trying to rotate the front drive shaft. It should rotate fairly easily. If you can't turn it your ADD is stuck in gear. The stuck ADD won't explain your engine issue, but would explain why 4wd works even with the disconnected vacuum hose.
01-05-2018, 10:52 AM
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If you have a missing vacuum hose that could be upsetting the engine when the VSV switches to that open port. Try capping that port and see what happens. Your ADD could be stuck permanently in gear (the green light would still switch on/off with the transfer case position). You can check the ADD by putting the vehicle in 2wd with the engine running, and then shutting it off and crawling under it and trying to rotate the front drive shaft. It should rotate fairly easily. If you can't turn it your ADD is stuck in gear. The stuck ADD won't explain your engine issue, but would explain why 4wd works even with the disconnected vacuum hose.
So after further looking around I realized that the nipple without the hose is the bottom nipple going into the wheel well to the canister and is a dummy vacuum port going to nothing. I have a t connection that takes both hoses to the top port which is linked to the vacuum tank in passenger wheel well. So I guess I’m back to ground zero. I did see the I think I have the wrong egr vacuum modulator that has only one port running to engine and then is hooked directly to egr valve. There is one hard line capped in the front of engine that is supposed to go to the modulator as well. Just ordered new modulator. Also I am missing the vacuum check valve for the pair hose. It’s suposed to be orange. It’s missing. Where can I buy one of these?? And could these cause add problems.
01-06-2018, 03:34 PM
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Still no progress
Ok. I replaced egr modulator with correct one and replaced every vacuum hose. I am still having issues with 4wd. I would think that if something g was slipping my rpms would jump as I lurched around. All rpms are affected. Found a straight dirt road and pushed it to 35 mph and experienced the surging all the way though. Every time it surges the rpm is dropping. Literally like I am taking my foot off the gas. It feels like it’s “missing” however there are no problems in 2wd. In fact it seems a little better after all the new vacuum hoses. The only thing I did not get to replace is the orange vacuum check valve coming off the pair hose. I am really stumped. Could my throttle cable be out of wack. It only in 4wd???
01-07-2018, 05:34 PM
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when you say jumping around, you mean the engine is stalling or the drive train is binding up? not sure what all has been done to the truck but i bought a half done project 1st gen a while back and it had a factory 4.30 rear with a 4.10 front.. no drive shaft when i bought it so i didnt notice until i got one put on. any play in the front drive shaft? check for grease-locking on it, but i think with add its always spinning anyways.
01-07-2018, 07:24 PM
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when you say jumping around, you mean the engine is stalling or the drive train is binding up? not sure what all has been done to the truck but i bought a half done project 1st gen a while back and it had a factory 4.30 rear with a 4.10 front.. no drive shaft when i bought it so i didnt notice until i got one put on. any play in the front drive shaft? check for grease-locking on it, but i think with add its always spinning anyways.
No binding going on it happens intermittently as I am pushing the gas pedal the engine literally cuts out for a split second. If I take my foot off the gas she is smooth at all speeds. As soon as I accelerate it just starts hesitating. I replaced the hose under the driver side wheel well going to the vacuum tank today. I missed that one. Drove down the road and thought I got it. No stutter until 2nd gear and about 20mph it stuttered but not repeatedly. I’m pretty sure I have a vacuum leak but am stumped because I just replaced all the lines. It’s almost like it holds vacuum for a short duration and the. Let’s it go momentarily before regaining vacuum.
01-07-2018, 07:32 PM
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5speed. In 4hi. Foot on the throttle increasing rpm with dead spots throughout. Runs perfectly in 2wd. Hard to capture on video. I am close to just tearing out all the vacuum lines grabbing a hose clamp and deleting the ADD all together but I would like to get it figured out.
01-16-2018, 04:32 PM
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Still super stumped
ok. I don’t know where to test the power. However I ended up getting the check valve going to the pair and then doubl checked all vacuum lines. I decided to cap the ADD Lines and the line going into manifold and at diff. I did this to see if doing the add delete would solve my issue. As soon as I shift transfer case to 4wd I still here the click and the rpms drop. 4wd is not engaged because there is no vacuum. Start driving and same thing happens. As soon as I push hard on gas it starts cutting in and out after getting to about 40 mph in 4th and my throttle evens out it smooths out. As soon as I push the pedal hard for power it is sluggish. So what is happening at the ecu when the transfer case lever is shifted to 4hi and the rpm drops? This is totally messing me up. Please any info is helpful.
01-17-2018, 01:45 PM
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Next thing you might try is to pull the connector off the transfer case, so that nothing electrical knows whether you're in 4wd or not. (the connector is up on the passenger side of the tcase, toward the top. Not easy to reach, but doable.) If the problem goes away even with the tcase mechanically in 4wd, you know the problem is electrical. Then you can start breaking the connections further and further from the tcase until you find the offending part.
