90 - Running out of breath at 5000 - No Codes

[dondon]

Trying to figure out why my 90 5800 mile ZR1 (new owner) completely runs out of steam at 5000 RPM, it doesn't pull particularly hard to that point and really badly from 4000 RPM.

Background:
I previously had a code 61 - which I ended up replacing the solenoid, vacuum canister and secondary plastic piping. I checked the actuators and both openned quite easily. The car no longer throws a 61. When reassembling the solenoid had an extra nipple which I plugged (don't do this). which led to a hard code 56. Upon removing the plug, the 56 has gone away. The only modification that the car has is a Haibeck chip which is slightly detuned to handle the 90 Octane ethanol free gasoline.

I'm a bit of an odd case judging by other forum members in that I have original injectors, I don't believe the car should have injector problems as it has always run ethanol free gas. The fuel I'm using currently is 90 Octane Ethanol Free, as sold at a local Sonoco station.

Anyway, at this point I'm not getting any codes coming back. I've attached a datalog from datamaster. Its short and hopefully it tells enough of a story. Anyway, any assistance would be greatly appreciated. I haven't owned the car since new, so I can't say I know what a clean pull feels like, but as it stands the car quite often feels like it hesitates, and even at times it feels as though spark is cut momentarily then the car starts to pull again.

Any thoughts would be greatly appreciated.

[efnfast]

Sounds like the secondaries are not operating.

[dondon]

Originally Posted by efnfast

Sounds like the secondaries are not operating.

Thanks for the input. My thoughts are identical to yours... I just am at a loss as to how to get them to open. Especially given the actuators work, no code 61 and in the datalog, the ECM thinks the secondaries are open.

Does anyone know where in the FSM to look, or a local to Tampa/St Petersburg/Clearwater expert to talk to. I'd love the satisfaction of fixing it myself, but the end goal is to have another well running Z on the road.

[Paul Workman]

Assuming you have a "FULL POWER" indicator when the secondary's switch is ON, no codes, then I wonder now if you've got the "accordion" plastic intake tube is collapsing syndrome.

Mine was collapsing, at around 5000 rpm and falling on its nose too. It is a common problem with those old plastic "snorkels" - especially when the under-hood or ambient air temps are on the warm side. However there is cheap and easily fixed either by installing some of Marc's wire hoops to support the tube, or do as I did and build a sheet metal sleeve that slides inside the tube to smooth the air flow and keep the tube from collapsing.

Just a thought!

P.

[efnfast]

Good thinking Paul, does the new owner know how the seconday key works, and there is a light on the DIC that says "Full Engine Power"

[dondon]

Originally Posted by Paul Workman

Assuming you have a "FULL POWER" indicator when the secondary's switch is ON, no codes, then I wonder now if you've got the "accordion" plastic intake tube is collapsing syndrome.

Mine was collapsing, at around 5000 rpm and falling on its nose too. It is a common problem with those old plastic "snorkels" - especially when the under-hood or ambient air temps are on the warm side. However there is cheap and easily fixed either by installing some of Marc's wire hoops to support the tube, or do as I did and build a sheet metal sleeve that slides inside the tube to smooth the air flow and keep the tube from collapsing.

Just a thought!

P.

Hi Paul,

I will go out and purchase a stocking, make a temporary air filter and eliminate the snorkel to see if that is the issue. I have doubts on the snorkel theory as the car is smooth to 4500-5000 ish with the power key off, when the key is in the full power position, the car does all kinds of miss behaving prior to hitting the 5000 mark.

Thanks for the input, I'll likely get to this around Wednesday... have lots of crazy project work to do this week.

Thanks again
Jonathan

[dondon]

Originally Posted by efnfast

Good thinking Paul, does the new owner know how the seconday key works, and there is a light on the DIC that says "Full Engine Power"

Yes, sir the DIC shows Full Power. I would say that the key isn't perfect though, as I turn the key to where the on should be then have to rotate it back a smidge to get the light to turn on. Not sure if its possible that it could be switching states while driving, but the light stays strongly illuminated.

Best Regards
Jonathan

[efnfast]

My key can be a little tempermental. I think the contacts are dirty. I have to cycle the key sometimes to get it to activate

[Franke]

My key did the same thing until I took the switch apart and repaired/adjusted the contacts. It is important to the ECM that the switch is not flaky.

[dondon]

So, I looked through the datalog and noticed a bunch of knock. I put original PROM back in... things seemed better right off. So then I went to go drill it.

Code 61 - 5K max, but relatively smooth compared to before. So now what, did I install a faulty solenoid? bad vacuum canister? ECM?

Any thoughts on what I'm missing apart from the 5 hrs on Sunday. I really thought I got that 61 and fixed it.