duowing

Ok, so I got myself that 280zx turbo. It made the 2 hour drive back home fine. It has some issues with accelerating, one of the most notable was that around 55-65mph it seemed like it would have trouble getting up sometimes and then other times it would be fine. Then from 65+ in Drive the car would seem to accelerate fine. Every so often as you would try to accelerate in these odd areas you could hear and feel a pop, the car would lurch forward just a bit and then lose the acceleration. On idle the car seems to idle around 1000rpms, it seems to have a bit of a pop through the exhaust every so often, but other than that it seems fine. Car doesn't overheat or smoke. The car would only start to get to half temperature when I was driving in second around 5000rpms. Other than that everything seems to be fine engine wise. All the plugs look fine, the distributor caps contacs look clean, the rotor looks good. I've heard something about a vacuum line that runs to the turbo wastegate? Where is the wastegate located? One other thing the guy had mentioned is that he once mesaured the fuel pressure and said he read it at 35psi of pressure and said he thought it's supposed to be at 40psi. Also the car seems to run better once it's warmed up. Any ideas?

SHADY280

sounds like you gotta check the timing as well as check for dirty coolant sensors, it doesnt sound like turbo, but i could be wrong. check the simple stuff first.

duowing

Could you elaborate more on the coolant sensors?

jfairladyz

If the motor runs better after it has warmed up then I would start trouble shooting the air regulator. It will cause issues before warm up if it's malfunctioning. Fuel pressure should be about 36...so 35 aint too far off. As far as your high speed hesitation (or whatever) problem, does it seem to be dependant on throttle position/input??? Or engine speed??? Or is it strictly between those speeds?

You wastegate is inside the turbo. You can see the actuator sitting on top of hte turbo. Its a large diaphram with a rod to the wastegate lever on the turbine housing.

I dont think your problem is turbo related.

duowing

Well I'm curious with a few things. Does the non-turbo have an EGR valve? Also for the air regulator, would the non-turbo's air regulator be compatible with the turbo? I'm thinking if I can start swapping parts between my two Zs to try and trouble shoot until I find the problem, then just buy the needed parts. That would prolly be the cheapest and best way to do that.

jfairladyz

not all the non turbos had EGR. But most did. The air regulators, electronically are compatible, but the two are not physically a direct swap (though I'm sure with a little tweaking you could make the swap). The only difference is the turbo version has the coolant passages built into the regulator. The non turbo uses has the air regulator mounting to a seperate coolant block. If you transfer this part over to the turbo with the air regulator then it should work fine. And if there is a problem and it doesn't work, it didn't cost you anything

duowing

Well I noticed that in the Haynes Guide for the non-turbo there is no EGR listed, but I see the EGR sitting right there under the hood of my 2+2. So I figure come tomorrow I'll start messing around. I'm thinking I'll also put in a new fuel filter and see if that causes any change.

NismoPick

I highly doubt this prob has anything to do w/ the EGR. Do as J is saying & check out the air regulator. Make sure the hose from the J-pipe to the tubing associated w/ the air reg isn't pinched. It will idle crappy when cold if that is pinched.

duowing

Like I said idle seems to be ok, It's just once you start to give it gas is where it will have problems. But Yeah I'm definitely going to take all the advice I can get to work this out.

jfairladyz

does it have these problems at all after it warms up?

duowing

It still does have some problems to an extent after it warms up. The idle seems to get even smoother. The car seems to get up and go alot better from a stop, but it seems like through certain speed ranges it still has these hesitation problems. This was still after about an hour or so of straight driving. The car was doing better, but at time I could leave it in drive and drop down to 55. I could give it gas and then the car would get right back up to 65 and over. Other times it would have a lot of trouble and very very slowly get back up. I'd kick it down to 2 so that way it seemed to get more power and pull itself back up. Like I said above 65 it seemed to be alot better, not perfect, but it drove more naturally. I can feel the turbo kick in and give boost. The car will drive at freeway speeds, but there is popping from the exhaust most noticeably upon acceleration from around 55-65 mph, it might be more related to RPMs. So I'm thinking the car's running lean, and it'll have more of a smell from the exhaust that my friend kept complaining about. Alot of the hesitation troubleshooting, seems to come back to the fuel filter or EGR valve. So that's why I'm thinking I'm gonna mess with those. As said the car didn't overheat and the temp gauge was always between 1/4-1/2 of the way on the gauge. My friend said he'd see a puff of smoke when I'd accelerate, but it was cold and rainy, plus I'd kick it down to 2nd then be up around 4k rpms or so. That was around when I was getting the popping too.

jfairladyz

sounds like the car is dumping too much fuel...which would explain the bogging, stong exhaust odor, and the puff of smoke. Might want to look into cleaning up the AFM a bit to see if that helps. While you're at it, go through and clean up ALL the electical connectors.

PooFlinginMonke

Clean off the cylinder head temp sensor contacts and wiggle the connectors on the ecu while you drive.

Post results if possible.

duowing

I was also thinking about seafoam. That might be a good try to run through the vaccum lines and what not. See if that helps at all. My question is do most places carry it? Also how do I go about introducing it into the system.

duowing

Ok, so put on a new fuel filter, but a nice amount of gasoline spilled out, so I'll give that a try, but we did a test. We pulled off the connector to the Air Regulator and started the car. It ran kinda crappy and would at times stumble around 2000rpm, then it could jump up and over and it act as if it were normal. So I turned the car off, plugged the connector back in and turned it back on, for the first few seconds the car seemed like it was normal, but then it just went back to the same exact as having the connector to the air regulator unplugged. So I dunno how well this could state that it's the air regulator or not, but I think it's a good start. I'll have to get a multimeter and test to make sure that there's power going through the connector, also where can I get a new Air Regulator? Finally what's the best way to go about using Seafoam? I picked some up, I'm gonna run that through, but I've never messed with this, so I don't know the best way to run it through the car.

jfairladyz

The air regulator connector would only affect the car as it warmed up. While it's cold the connector has no affect on the car. It's simply meant to heat the internal spring element to help close the air regulator as the engine warms. Nothing more, nothing less.

duowing

So today, we went ahead and did the AFM rebuild thing. The AFM wasn't really dirty, we adjusted the inside, and put it all back together. We plugged it back into the car, and it seemed to make no difference if it did just a little.
At idle cold the car seems to have an issue with revving around 2000-2500 rpms. As it warms up the car will rev very easily and seems to have no problem while sitting in park. You can hear what sounds like a slight miss every so often while idling, but the car idles very smoothly around 1000 rpms. The most notable thing is that while revving the car in park it seems like there is a miss around 2500 rpms. So we get to driving. The car seems a slight bit sluggish, but at least while warm(didn't try it cold). If I seem to get on it more than half it will start popping through the exhaust. I hear the pop coming from the engine bay and feel the car jerk. Sometimes it seems like it will be ok then start really accelerating, essentially as long as I was at about half throttle I was pretty much ok. I noticed that a good portion of the time the boost gauge was close to going on red when I would get the pops. While going on an uphill turn off ramp from the freeway it seemed like the car had alot of power and accelerated well, then around the turn.

On the way back from my destination I took another run on the freeway. In Drive I held the car at about half throttle. I felt it get some boost going, and it was quickly accelerating down the freeway ramp. Once I hit about 60(around 3000rpms) it feels like it kinda dies. I don't know if it's because I just need to give it more gas or what. If I mess around with kicking it down to second 2 I can at times get it up to about 65 where then I can put it back to Drive and seem to go ok. Could this be a fuel pump issue? Something with the turbo? Maybe the AFM is on it's way out? One other thing I've been questioning. Is it possible I have low compression in a cylinder? It wouldn't make sense considering the car seems to go pretty well and doesn't smoke. I'm not real good with this stuff yet, so I'm not sure. I'm still going for any advice. I also hear to check timing, but how do I do the timing with a Turbo?

NismoPick

Just like normal, but disconnect the TPS connection when timing. The timing on the L28ET should be set @ 20 degrees.

jfairladyz

Make sure your timing is right and make sure all the injectors are FULLY firing. A partially clogged injector will still fire, but it will be weak. This will also cause a sluggish engine. And thats if all 6 are actually firing. Same for spark, make sure you've got full spark at each cylinder. It sounds like you're not firing on all 6. Pull the spark plugs and have a look. See if you can notice a difference between any of them as far as their overall condition is concerned.

EDIT: also, if your problem seems RPM dependent then it could be your AFM. The board in the AFM has a series of resistors. If one of these or its track goes bad then the ECU wont get a proper reading when the AFM flap crosses that resistor. hook up a meter and put the flap through its arc and see if you get an abnormal resistance reading.

duowing

I've pulled the plugs, and they all looked pretty similar, I'll have to go back and check the gap on them I believe the gap should be .044 or something like that. Also how do I go about testing I have full spark at each cylinder? As for testing the AFM, am I able to test it while the AFM is out of the car? If anyone has a working AFM from a turbo they'd be willing to send to me for cheap, I'm interested. I'm just hoping that I can slowly work this out. Also will all that really loud popping through the exhaust cause damage? Also I was thinking about the timing. The guy at some point started having problems. He put an entirely new distributor, cap, and rotor in the car. My guess is he probably never set the timing. Also the other reason I mentioned setting the timing with a turbo is that Haynes says you have to set it through the crank angle sensor?

jfairladyz

with the 82-83 the CAS is in the distributor housing. So rotating the distributor in turn rotates the CAS to change the timing. Just set the initial timing the way you would an NA on yours since you've got a later model (only it should be 20 degrees instead of 8 )

On 81 models the CAS is on the front of the engine though.

duowing

As for the difference with the whole being cold and warm, in the Haynes it mentions that the car runs differently between cold and warm, something involving vaccum advance and stuff, I mean even though all of that is controlled by the ECU, if the timing is off, wouldn't that then cause it to be odd just like on the NA?

PooFlinginMonke

You still haven't wiggled the connectors on the ecu while driving.

Since this happens to most every single 280zx turbo I have seen, it would be wise to try it at the very least.

jfairladyz

I'm not sure I'm exactly following you on this one...the turbo doesn't have any vacuum advance, or mechanical advance. Thats NA only. Turbo uses electronic advance for all situations. But where the ECU places that advance is dependant on where you put the initial timing, cause that is the ECU's reference point. Where ever you set the initial, the ECU will think that it's at 20degree's initial. So everything the ECU does will be based on a 20 degree initial timing. So yes, if the initial is off then the ECU's advance will be off. Set the initial to 20 degrees. You set it the same way you set the non turbos timing except there is no advance to disable. The ECU will take care of the rest.

And for the love of pete, try Poo's suggestion. It's got to be the easiest one yet But definitely make sure your timing is right. That will screw everything up.

duowing

Alright we have the 20 degree mark on the timing plate set, we just can't seem to find the notch on the crank to match it up. Is it on the plate of the crank that moves right along that timing plate?