So my paint job has again reacted as soon as it got hotter, again. Crazing/cracking...the only option is to strip to metal an try again, for which I no longer have facilities. That's not the issue though.

 

As mentioned before I have a running problem, I've pulled codes 34 (knock sensor) and 12, MAF (but that should be because I had it disconnected). Even if there is a knock sensor issue, would this cause the engine to stumble and stall?

 

The car runs great until I connect the confirmed 'good' MAF. So this suggests pump, injectors and coils are fine. Maybe an air leak then...

 

The engine used to run fine 5 years ago, and so can't be a major issue, gunk maybe. Although history is limited, the engine should have only done 64,000 miles.

 

In a nutshell, after 5 years I've had enough. Despite feeling a bond with the car I've rebuilt over the past 5 years, and not being the kind of person who gives up, I just feel that maybe I need to move on...

 

If the paint looked like it did when I first painted (which was amazing!), then at least I'd know I had a great looking car after fixing the running problem....but I wont now.

 

I have some time off work soon, and the plan was to pull off the plenum, replace with a clean shot blasted one, checking for any air leaks. I have the gaskets (except the IACV one). I was going to clean out the IACV, just seal it with gasket sealant. I have gaskets for the plenum and throttle bodies. Personally I don't believe there is an air leak. I did delete the EGR when the engine was out, but the plenum holes were sealed...it can't be that, but it's the only thing that's changed since the engine last ran.

 

I just fear this is the end. I just can't do it anymore. Maybe there is a time to just give up, despite everything you've given. I need to move on....

I would try and get the z running properly and then get it painted at a good paint shop mate. Or just sell up and buy another.

What a shame after all of your time and skill put into the car, sadly this though is a common thread with Zeds, what starts off as an exciting passion to create a car what you want, the time, effort and financial pressure along with a slightly unfulfilled dream outcome is too much.

 

Good luck with what ever you decide to do.

 

 

Jeff

So my paint job has again reacted as soon as it got hotter, again. Crazing/cracking...the only option is to strip to metal an try again, for which I no longer have facilities. That's not the issue though.

 

If the paint looked like it did when I first painted (which was amazing!), then at least I'd know I had a great looking car after fixing the running problem....but I wont now.

 

Sorry to hear mate and no offence with this, but you should have listened to the advise in terms of painting your car with cellulose or rather NOT to paint it in cellulose. It's awful stuff - only really suitable for painting radio controlled cars with.

 

I hope you don't give up on it. Maybe get the car prepped again by yourself and give it to a decent bodyshop to paint and finish of the top coat with quality 2k paint.

Edited May 29, 20178 yr by Funkysi

Why don't you spend a day cutting back the bad paint and get yourself a roll of Vinyl. It will look great for a few paces and it won't cost much. Gets you going and feeling positive.

The mechanics is probably not that bad in reality.

I'm not sure, but if it's consistently pulling timing because the knock sensor is teliing the ecu it's detecting knock (faulty sensor or it is actually knocking) then that would cause it to run lumpy until you disconnected the MAF and it starts dumping fuel into the engine to smooth it out.

I certainly wouldn't give up on the mechanical side of things. Doesn't sound like a big issue, just scrub everything you think you think is wrong and start from scratch and work through the faults as logically as you can.

Thanks everyone, after pondering it a while, thinking about everything I've done to date, I'm going to continue the battle for now.

 

I have considered vinyl, so that is an option, but I'm going to concentrate on the running issue first.

 

I'm going to pull the plenum, replace it, and whilst doing this I'm going to do the coolant bypass. I'll clean out the IACV and check that it's working. I'm going to replace the vacuum pipes with silicone ones.

 

Thing is, if the knock sensor is causing the problem then really I need to replace it...of course there's the greater issue that the engine is actually knocking. I know you can place a resistor in the knock sensor wiring to fool the ECU, but what about if I just disconnect it? I'd really rather not pull out the lower intake manifold unless I have to.

Thanks everyone, after pondering it a while, thinking about everything I've done to date, I'm going to continue the battle for now.

 

Great stuff matey, shame to give up now.

 

I know its easy to say 'take it to someone who knows these cars' but truly consider this. You could end up chasing rainbows with trying to fault diagnose a potential signal problem. I has a similar issue years ago; and after changing and swapping costly (known working) components, taking/shipping the car to a then "300zx specialist" (not trading on here for many years now, and not to be confused with the reputable few 300 mechanics), £2500 later the fault was still there. I learnt my lesson the hard way and to think it was a single 1mm wire with a partial break!

 

Once the mechanical side is sorted, it will give you back your mojo to crack on with the paint; 15 years plus later, i'm still here!

Thanks everyone, after pondering it a while, thinking about everything I've done to date, I'm going to continue the battle for now.

 

I have considered vinyl, so that is an option, but I'm going to concentrate on the running issue first.

 

I'm going to pull the plenum, replace it, and whilst doing this I'm going to do the coolant bypass. I'll clean out the IACV and check that it's working. I'm going to replace the vacuum pipes with silicone ones.

 

Thing is, if the knock sensor is causing the problem then really I need to replace it...of course there's the greater issue that the engine is actually knocking. I know you can place a resistor in the knock sensor wiring to fool the ECU, but what about if I just disconnect it? I'd really rather not pull out the lower intake manifold unless I have to.

 

Is your EGR still there or has it been removed. Ifs it's gone, you can get to the knock sensor without removing the lower plenum when your upper plenum is off. It's a faff, but doable. If so, replace the sensor and check the continuity from the plug to the ECU, and bobs your uncle you've eliminated one potential cause for your running problems.

 

If you're EGR is still there, how long ago did it last have a 60/120K service. If it's due any time soon, you're only looking at an extra 8 bolts and the middle idler pulley to get to the knock sensor

Is your EGR still there or has it been removed. Ifs it's gone, you can get to the knock sensor without removing the lower plenum when your upper plenum is off. It's a faff, but doable. If so, replace the sensor and check the continuity from the plug to the ECU, and bobs your uncle you've eliminated one potential cause for your running problems.

 

If you're EGR is still there, how long ago did it last have a 60/120K service. If it's due any time soon, you're only looking at an extra 8 bolts and the middle idler pulley to get to the knock sensor

I removed the EGR, but never had the engine running properly since. Holes are plugged in the plenum.

 

It's good to know I can get to the EGR without removing the lower intake though.

 

My time off has been reduced down to two days, as going to have to go into work now...perfect.. [emoji17]

 

 

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It may not even be the sensor itself. The fault, code 34 is "knock sensor circuit" not Knock sensor. You cannot simply remove it or short it, a broken or shorted wire will still throw code 34. In my case the loom itself was damaged. You can make a sub harness with an old knock sensor plug and solder in a 1mega ohm resistor tricking the ECU into seeing a functional if hyperthetical sensor. In any event it's functionality is limited, puts you into safety boost. At idle and off boost your not going to notice, it certainly isn't a limp mode. I think you can safely pop that one to one side for the immediate moment.

Do you have consult or equivalent?

No consult or anything, but something I considered. I remember reading somewhere to stay away from the Chinese leads on Ebay. It would be great if when I pull the plenum there's an obvious problem...like an EGR blanking playenthats not sealed...i don't have that kind of luck though!

 

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*EGR blanking plate.

 

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