280ZX Engine Trouble at Full Throttle

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Josh
Posts: 24
Location: Auckland

280ZX Engine Trouble at Full Throttle

Post by Josh » Thu Feb 05, 2009 9:44 am

Hi!

Problem with L28e.
- Generally runs very well (wheel spins around corners no problem :) )
- Idles very nicely (1500cold / 700 warm and very smooth)
- When it's at WOT it will hit the wall at ~4500 rpm
- This only happens at full throttle and only at high(ish) rpm
- If I take it easy (not foot to the floor) it gets to 5500rpm+ no worries
- Has had some of the anti-smog stuff pulled out (carbon canister removed and hoses terminated)

Spent hours on it so far.
Tried:
Swap ECU
Swap coil, leads, plugs, injectors, AFM, TB, fuel pressure reg
Check TPS (good)
Check vacuum advance (OK)
Check timing (OK)
Check all cylinders firing (OK)
Fuel filter seems to be clear
Compression seems to be good

I'm at a loss! Anyone got any ideas? The only thing I can think of is a fuel pressure problem so I might try changing pump...
1980 280ZX 2str, under reconstruction
1982 Datsun B310 Fastback - SOLD!
CBR250

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nzeder
Site Admin
Posts: 1503
Location: Auckland
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Post by nzeder » Thu Feb 05, 2009 10:08 am

Did you not sell the car? Why is this your problem? Surely the new owner knows he is getting a almost 30+ year old car that will require some work?

I don't speak txt so I have to ask What is WOT?

I think I have worked it out - Wide Open Throttle man that took some time I hate TLA that I don't know.

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ZILVER
Posts: 470
Location: Auckland

Post by ZILVER » Thu Feb 05, 2009 10:17 am

WOT -Wide open throttle?
High RPM resulting with severe vibration and noise usually relate to a drivetrain issues. At a guess the Driftshaft universals and bearings possibly worn.

nzniggles
Posts: 63
Location: Napier

Post by nzniggles » Thu Feb 05, 2009 12:28 pm

Sounds like a fuel pump running out of steam. Get a pressure check done at full load on a dyno (or a drive down the road)

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Josh
Posts: 24
Location: Auckland

Post by Josh » Thu Feb 05, 2009 3:44 pm

sry 4 txtspk :)

I thought WOT was a pretty standard acronym... maybe not? Yes it does mean Wide Open Throttle.
Yes the car is sold but I agreed to have a go at fixing the problem before the new owner picked it up. Thought it would be a quick fix... d'oh!!
1980 280ZX 2str, under reconstruction
1982 Datsun B310 Fastback - SOLD!
CBR250

Red eyeZ
Posts: 18
Location: Masterton , Queenstown

Post by Red eyeZ » Thu Jul 23, 2009 10:52 pm

I have got a similar problem with my L28E , it accelerates as normal but after about half an hour it starts to lose full throttle and misses and progressively gets worse untill you cant even touch the pedal without it missing. But when i turn the engine off and restart it the problem goes away , untill i drive another 20km then the problem starts to re occur .

BRONZEE
Z Club Member
Posts: 7186
Location: Auckland

Post by BRONZEE » Fri Jul 24, 2009 8:18 am

Red eyeZ wrote:I have got a similar problem with my L28E , it accelerates as normal but after about half an hour it starts to lose full throttle and misses and progressively gets worse untill you cant even touch the pedal without it missing. But when i turn the engine off and restart it the problem goes away , untill i drive another 20km then the problem starts to re occur .
Hi Red eyeZ, hiijacing the thread for a sec, do you know about the South Island tour?
http://www.zclub.org.nz/viewtopic.php?t=1451&test=test

Now back on topic. 8)

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willythefish
Posts: 127
Location: Rotorua

Post by willythefish » Sun Jul 26, 2009 1:33 pm

I have similar issues, could be the fuel pump or maybe the fuel pressure regulator.
Does anybody have ideas how to check the fuel pressure, where to connect in. Buying a cheap fuel presssure gauage is less $ that time on a dyno. Replacement fuel pumps are expensive if its not the problem.

nzniggles
Posts: 63
Location: Napier

Post by nzniggles » Mon Jul 27, 2009 12:42 am

You need to check the pressue in the fuel rail, so after any damperners, filters, etc but before the regulator

Normally you have
pump > filter > dampner > (**** you need gauge here ****) > rail / injectors > (**** or here ****) > regulator > return to tank

It doesn't rule out the regulator either but at least it's a good valid test and will give you a direction to head in

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Baker93
Z Club Member
Posts: 330
Location: Auckland

Post by Baker93 » Mon Jul 27, 2009 7:56 am

Having fuel pressure is all well and good and obviously very important, but most of all you need fuel flow or volume to go with it. Of course you would expect to see a pressuure drop if available flow was exceeded but with the number of dampers valves etc in a 280z who knows. The ideal place to check fuel flow is on the return line to the tank (again not being a 280z expert i assume they have one), there should always be a reasonable return volume even at WOT and full load otherwise you can assume the engine is consuming all it can get. Also depending on how smart these things are, if it runs out of fuel the ignition may be retarding further reducing power and a willingness to rev. I will make further enquiries with Greg as he played with this extensively.

Red eyeZ
Posts: 18
Location: Masterton , Queenstown

Post by Red eyeZ » Mon Jul 27, 2009 9:21 pm

My problem seemed very odd because it didnt miss under load , it was more relative to throttle position . I could be doing 100km/h in 5th and put my foot almost to the floor and it would pick up speed quite nicely but whenever i went WOT it would miss quite roughly , back off slightly and it would roar into life again .This problem only occured on long distance drives . The throttle position in which the missing occured gradually reduced over a half hour time frame to the point when i couldnt even touch the pedal without it missing. I hope all this makes sense . Im a diesel mechanic which probably explains alot!

nzniggles
Posts: 63
Location: Napier

Post by nzniggles » Tue Jul 28, 2009 2:00 am

A flow problem will show itself by indicating a pressure drop. If your pressure drops in the fuel rail, you have a flow problem. This could be from a duff pump, an electrical issue, clogged filter, damaged piipes .......... many many more. The first basic test to eliminate the fuel side from the ignition side is to measure the pressure but it must be under load to be a valid test. As you've said, it idles fine but hesitates under load - that's where you need to take your measurement. Flow is also a good check but does not take into account the possibilty of a crook regulator. The regulator could be failing, dropping fuel pressure but still returning a good flow back to the tank.
Last edited by nzniggles on Tue Jul 28, 2009 2:06 am, edited 1 time in total.

nzniggles
Posts: 63
Location: Napier

Post by nzniggles » Tue Jul 28, 2009 2:04 am

Redeye - your problem alost sounds like an ignitor module. As the temperature increases the output stage of the module starts to fail. Try swapping for a known good one as a test

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willythefish
Posts: 127
Location: Rotorua

Post by willythefish » Fri Jul 31, 2009 8:40 pm

I trolled through the FSM to see what Nissan recommend, measure fuel pressure after the filter before the fuel rail pipe
at idle 2.1kg/cm[sup]2[/sup] or 30psi
the moment the throttle is pressed 2.6kg/cm[sup]2 [/sup]or 37psi
The fuel pump has an internal relief valve operates at 43-60psi at the pump
Fuel pressure is regulated off the inlet manifold so throttle position (i.e.) vaccum makes quite a bit of difference.

Now I need to find the best value for money fuel pressure gauge anbody tried this?
http://www.omins.info/jonvy/line/1106/a ... hite-face/

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