90 - Running out of breath at 5000 - No Codes

[scottfab]

First off keep your momentum. Your tenacity will pay off.

Some ideas below. But what if it's not fuel and not the secondaries opening that is the problem? What if the CATs are blocked by soot etc on the front end? The symptom would be loss of power at higher rpm. My brothers vett had this issue. The bad new is I haven't the slightest idea how to check for that. On my brothers car I took the header off and looked down in there. I saw blockage and punched a long screw driver through the ceramic CAT. This fixed his problem but he then had to get new CATs. See below for ideas on secondaries.

Originally Posted by dondon

...snip...
CKT 930 is the connector to C17 (prior to removing plenum during previous diagnosing). Which when shorted operates the actuators... so can it be assumed from the above I have a bad ECM or are there some other tests I can run to avoid a potentially unnecessary parts spend or is it a case of just suck it up and try to source an ECM?

Based on the fact that you get some secondary action up to 5000 I'm going to say the ECM is ok. Based on the charts at the bottom of this page it the secondaries were not opening at all you'd get no big pull up to the 5000 mark which I assume you are. That shows the ECM signal works. You could also verify the voltage at C17 while driving. It should go to 0V and stay there at WOT. If it does and the car still flattens at 5000rpm that shows the issue is not with the ECM and likely not with the secondaries based on the other C17 test you did.
http://www.zr1netregistry.com/Inform...Diagnosis.aspx

Originally Posted by dondon

I have the plenum off and will likely leave it off until I'm sure I've tested everything that could be a miss. So any other good tests to get through would probably be good to get out the way.

Thanks Again

Before reassembling rig a wire onto the each actuator such the you can physically pull on one and then the other as you are at 5000rpm and you feel the sag. You have to be creative in routing the wire using the wiper shaft as a pulley then around through the window. If power returns you need to stay looking at the secondaries and not fuel or CAT blockage.
ALSO before reassembly.....
Just for grins. Can you disconnect the pump way up where it connects into the vacuum reservoir tank? Then turn the key on to activate the pump. Does it continue to run >60 sec? Now plug the line you pulled. Does it run <10sec? The "re-verifies" that the pump is not blocked AND that it's vacuum contribution is making it to the reservoir.

[A26B]

If concerned about the secondaries not opening fully, just tie them open & go for a drive. It won't hurt a thing & if it runs out great, you will know for sure it's a secondary port throttle issue.

[Franke]

Some more thoughts. In a previous post you indicated a intermittent code 61 then later a solid code 61 in full power etc. Have you checked the sec solenoids for amount of vacuum needed to open the secondary's as suggested in Marc Heibeck's ZR-1 specialist test. Should operate at about 6 inches of vacuum. Also, the FSM says that there are various sensor inputs in an acceptable range required by the ECM to turn on the secondary's.

[dondon]

Originally Posted by Franke

Some more thoughts. In a previous post you indicated a intermittent code 61 then later a solid code 61 in full power etc. Have you checked the sec solenoids for amount of vacuum needed to open the secondary's as suggested in Marc Heibeck's ZR-1 specialist test. Should operate at about 6 inches of vacuum. Also, the FSM says that there are various sensor inputs in an acceptable range required by the ECM to turn on the secondary's.

The code 61 is an intermittent code 61. My apologies for not stating that correctly. I did receive a solid 61 when I tried to be smart and trick the computer but adding vacuum to the sensor and keeping vacuum on it. I think the sensor assumed there was an issue with the solenoid since I believe (and I'm an amateur) that the vacuum only exists when the solenoid is activated. So the computer knew that it was being messed with and set a 61.

I did have a chat to GK today for a bit, he isn't of the belief there are ECM problems and gave me a laundry list of other things to check prior to going the ECM route. I'd love to know a hard and fast rule for knowing you have an ECM problem.

For the benefit of others GK mentioned that the power key even though the light is on requires a very strong connection and so I should recheck that as well as checking the pins on bolt on connector to the plenum, to ensure I'm getting a good ground. So I'll start there and keep working at it.

Thanks again to everyone for the continued support with this issue.

[dondon]

Today it lives. Took 5 months of very part time tinkering and it finally does everything that was expected of it.

So the problem appears to have been 2 fold. The fuel pumps, even though I could not confirm the others were shot, at bare minimum their check valves did not work, they were replaced with the rather well priced $23 models... This made the car run a lot smoother, but the 5000 issue persisted.
Today, I was staring that that ECU and wondering what kind of black box magic it was performing since everything about it seemed to work with the exception of the secondaries. On advice from another forum member I continued tinkering instead of getting it rebuilt. From pure irritation since if the C17 pin were shorted the secondaries opened I took the harnesses off of the ecu and stared at them for a while, tugging and pushing on C17 to see if it were somehow loose. Anyway, put it back together did a secondary output test and saw the secondary vacuum pressure go up... something that hadn't happened prior. I went for a spin and like magic it ran well.

So in summary new fuel pumps and a loose ECU connector?

I'm sure I'll likely have an issue with this again at some point, but for now HAPPY DAYS!

[Franke]

Good for you Dondon. Way to go!