My 1982 ZX Turbo automatic has recently started having a problem accelerating between 60 and 70 mph. I just took it out for a test run to nail down exactly whats happening. At lower speeds like 30 or 40 miles an hour, when I floor it, I get plenty of power, although my boost meter never gets higher than about +3. At 60 mph, or about 3300rpm, the car basically stops accelerating, very slowly creeping up in speed. The boost meter holds steady at +3. At about 70 to 75mph, the power kicks back in and the car then accelerates nicely. A few times when I did this, there were backfires out the exhaust, but not every time. Also, the warning indicator light (the thing that checks the headlights, washer fluid, etc) comes on at 60mph, and then goes out above 70 or when I slow down. No one thing is displayed - it looks like all the items are failing. I checked everything it tests, and all is ok. Nothing else wierd is happening that I can tell - all guages read normally - when the power loss occurs.

Anyone got any ideas? Thanks in advance.

1979 ZX (sold)
1982 Turbo automatic coupe
2006 350Z

 

Sounds like it might be leaning out on you.

Start with the simple stuff...

Fuel filter first.

Then the basic tune-up items should be checked and replaced if needed.

See how that goes and get back to us.


Rod.

 

Interesting how the warning light comes on when it's acting wierd... that warning system has nothing to do w/ the engine, just car components (lights, coolant, fluid, etc). It turns red, then goes back off? That would be an electrical problem....

As for the accel prob, like Rod said, start w/ the basics... Spark plugs, wires, filter, hoses, etc. Also, has the AFM ever been tampered with? It kinda sounds like a fuel problem. An air/fuel ratio gauge will tell you what is going on during the accel prob.

 

+1, try a tune up then see if it still does it

 

Yeah, I was harping on the relation to the warning lights and the surge on certain load problem. Actually, the electrical system IS related to the engine, and, as you know, the sensors send signals to the ECU. Also, we cannot assume anything, so we must ask TomJohn to clarify the problems he's having:

1. When was the last time your Z had a tune-up (air filter, fuel filter, spark plugs, plug wires)?
2. Have you checked the timing recently? (That alone sounds like the problem, but we won't know until we receive your feedback).
3. When was the last time your Oxygen Sensor was replaced?
4. How old is your battery?
5. How old is your alternator?
6. Have you had ANY problems whatsoever when starting your Z?
7. Has the car sat for longer than 3 weeks without being started up?
8. Although you said all gauges were "normal" when the problem occurs, did you specifically look at the volt gauge? If you're not sure, please do so the next time you have the problem, as it's very important.
9. When did your Z last pass an emission inspection, if your county requires one?
10. Do you hear any noise whatsoever when the problem occurs? Please turn off your stereo, just so you can find out.

Answering the above questions will help us greatly in understanding more about your problem.

 

Not sure why, but the problem seems to be solved! The car is now running fine. What I did:

Pulled plugs - they looked good - tan with clean electrodes. I checked the gaps and they were fine.

Pulled dist cap and cleaned rotor and contacts

Ran a full diagnostics with my ECCS Analyzer. Everything checked out OK except the speed sensor test, which I didn't do as you have to get the rear wheels off the ground.

At any rate, the car now pulls fine throughout the rpm range with no backfiring or warning lights. My guess is a corroded connection to the ECU that got cleaned when I unplugged the harness to plug in the Analyzer. I will go back ASAP and thoroughly clean all the connectors.

Thanks to everyone for their suggestions. I will also check some of the items mentioned by Z Car Barbie. This forum rocks!

 

how'd you come across the analyser? ( if you dont mind me asking) Those are a rarity. Good to see things worked out for you

 

I forgot to mention in my prior post that I did a compression check when I had the plugs out. These are the results with a hot engine and WOT:

Dry After adding some oil
#1 145 155
#2 145 155
#3 150 160
#4 150 160
#5 150 160
#6 150 160

These numbers seem reasonable to me for an engine with about 120000 miles. Could I be looking at a head gasket problem with cylinders #1 and #2?

I got the Analyzer off eBay for $275. It works great and is simple to use. It test about 18 different components, including the CHTS, detonation sensor, idle control, all injectors, and more.


1979 ZX (sold)
1982 Turbo automatic coupe
2006 350Z

 

Your compression is actually pretty much perfect for the turbo car. Stock compression for the turbo cars is 140 per cylinder.