Plenum Pull Advice, Starter Rebuild, MAP Sensor Info

[mgbrv8]

That is a great link Dynomite thanks for sharing. I have a basic question about our cylinder order is like the picture below?

Dave

[Dynomite]

Originally Posted by mgbrv8

That is a great link Dynomite thanks for sharing. I have a basic question about our cylinder order is like the picture below?

Dave

That is it exactly........Number 1 and number 6 are 360 deg separated.
When number 1 is on compression, number 6 is on exhaust.

Drivers Side from Front to Back.....1357
Passenger Side from Front to Back......2468

[mgbrv8]

Okay Gentlemen I need your help today I started the car for about a minute. I noticed that it has a very subtle miss. Now here are the possibilities The injectors I purchased about a year ago and They have been sitting on a shelf so maybe one might be stuck. Second may be one of the coil packs are bad. Do you guys have any idea what might be Or how to check for the problem.

Secondly Since my a/c system is completely rebuilt. With a rebuilt compressor, new accumulator, And a new condenser. All my lines are flushed. I think I am not going to go with r12 But I also know our 134 is less efficient. A friend of mine recommended freeze 12. Would that be a good substitute for r12 Or is there another option??

Dave

[Marc Haibeck]

If the misfire is light, it’s harder to isolate. An easy way to test fuel injector flow is with a fuel injector pulse tool. It’s outlined in the GM service manual. You don’t have to use the GM tool. The pulse tool should be easy to find in a tool catalog. Rather than remove the plenum you could use jumper wires to connect to the fuel injectors at the ECM A connector.

A 820 microfarad capacitor can be used as a simple substitute for a fuel injector pulser. Discharge the capacitor by connecting the leads together. Disconnect the A connector from the ECM. With the ignition on connect the positive side of the capacitor to a fuel injector and the negative side to ground. The fuel injector circuit will charge the capacitor. The fuel injector will flow while the capacitor is charging. It will flow for about one half second. Discharge the capacitor and go to the next injector. The charge time of the capacitor is very consistent so accurate fuel pressure drops can be recorded for each injector.

I’m assuming that you don’t have access to a scope. If you did you could measure spark plug burn time. A spark viewing tool would let you visually inspect the spark available at each plug. A spark viewing tool can be found for less than $10 at a good auto supply store.

I have found that a ZR-1 AC system is just as efficient with with R134a refrigerant as R12.

Best of luck.

[mgbrv8]

Okay first off It's been a while since I was able to touch my Zr1 project. What happened was I got everything buttoned back up But once I started it I noticed a miss Using my stethoscope i pinpointed which primary injector was stuck Despite tapping I could not get the stuck injector loose. Needless to say I had to pull the Plenum back off again. Once I had the Plenum off I tested all my injectors with a 9 V battery. Only to find that four of the secondaries were stuck. Once they were all free I energized the fuel pump circuit Via The fuel pump pigtail that hangs off the main harness from the ECM. Once the fuel system was energized I then found that I had six secondary And two primary injectors Leaking. So the lesson here is if you ever do a injector Replacement or anything in the valley Make sure to test your injectors before putting the Plenum back on. Now my injectors were rebuilt by a company that a number of people Have used on this forum. Before I go naming names or pointing fingers I want to talk to them on Monday.

Dave

[Paul Workman]

Originally Posted by mgbrv8

Okay first off It's been a while since I was able to touch my Zr1 project. What happened was I got everything buttoned back up But once I started it I noticed a miss Using my stethoscope i pinpointed which primary injector was stuck Despite tapping I could not get the stuck injector loose. Needless to say I had to pull the Plenum back off again. Once I had the Plenum off I tested all my injectors with a 9 V battery. Only to find that four of the secondaries were stuck. Once they were all free I energized the fuel pump circuit Via The fuel pump pigtail that hangs off the main harness from the ECM. Once the fuel system was energized I then found that I had six secondary And two primary injectors Leaking. So the lesson here is if you ever do a injector Replacement or anything in the valley Make sure to test your injectors before putting the Plenum back on. Now my injectors were rebuilt by a company that a number of people Have used on this forum. Before I go naming names or pointing fingers I want to talk to them on Monday.

Dave

Dave,

If it is who we think it is, their reputation is to make it right. However, you might be interested to know that your situation is not unheard of with "rebuilt" injectors. Even if the bad ones were to be replaced at no charge, you still have experienced what has happened a number of times before (with rebuilt - or NOS injectors too, come to think of it). But, the choice to go cheap and roll the dice (16 times) on "rebuilt" injectors and not come up "snake eyes" is the buyer's choice...and too possibly another set of gaskets to go with the additional plenum pull So, I believe the consensus on the forum is to go with their new stainless injectors once and be done with 'em!

This may not amount to anything, but I noticed you used a 9v battery to actuate the injectors. That is the first time I heard of using a 9V battery to test the injectors, so I'd be at a loss to say whether or not that in itself could be an issue if one or more failed to function. (I used a jumper directly off the pos of the 12v battery to test if they functioned properly (switch ON, fuel rails at pressure). Course, it doesn't matter in the case of a leaking injector - leaking is leaking.

Well, it sounds like you're on the road to repair. Let's hear how it turns out.

P.

[Bob Eyres]

Not trying to highjack the thread, but do the companies that offer new injectors offer a test service that will flow match injectors before delivery?

Way back in the day this seemed to be an issue with new injectors, and the prudent course at the time was to have them flow matched so that they would be identical. That would establish a perfect baseline for further tuning.

I haven't heard of this being done recently. Is this service still available?

[Franke]

The one behind the plenium had a wet oily film in it when you pull the hose. My guess is that there is a rubber diaphragm in there and the oil might cause problems and a false reading.

Dave

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Last edited by mgbrv8; 03-06-2013 at 06:00 AM.

I had a map sensor fail. It caused the car to cut out and die several times until the ECM took over and set a value based on the TPS. I cut the map open to see what gives and found a 10 ohm resistor came off the solder pads. The vaccumn port sensor on the circuit board appears to be a solid state device and is sealed except for a very tiny hole in the middle of a metal disk. Under the disk is a tiny solid state device with several leads and this device has a clear spongy film covering the surface that the metal disk acts upon. The entire circuit board (not the solid state device)was covered with a gelatin Like substance which i believe prevented dirt and moisture contamination. My MAP sensor had a 3/4 volt lower output than the new one i installed before it went intermittent. The entire circuit board measures about 1 inch wide by 2inches long. The rest is all plastic filler material.

[mgbrv8]

Very cool thank you for the info sir.

Dave

[mgbrv8]

Okay I got the new injectors in and he included an new set of plenum gaskets. I first tested the new ones with a 9v battery to just make sure they weren't stuck. I then checked the resistance and marked each one. Tomorrow I will install them and test them and and do the purple starter wire mod.

David