Maintenance on my '94 z28 pic heavy

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Originally Posted by Injuneer

I'm not sure what function those 2 small holes just above and to the side of the pintle serve. There are no matching holes in the gasket or in the intake manifold.

The factory manual indicates the valve should hold vacuum for at least 20 seconds.

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I couldn't figure that out either. I tried to clean them out, but they are just holes.

Most of what I learned was from here.

http://www.tomco-inc.com/Tech_Tips/ttt27.pdf

The 2 little pintle holes on the tipa keep the pintle closed incase manifold vacuum keeps the valve open. It took me a while to understand it. There's a lot going on for such a small part.

Mine held open for as long as I held my thumb. I couldn't blow threw at all once it was clean. Glad I don't have to blow the pintle anymore haha.


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I've got an update and some more questions. I finally got the o2 sensor changed. Haven't ran a log yet. It's been rainy/wet roads so I can't hear the car very well, but it sounds like the idle is better.

My question is about the pulley driven stuff. I haven't been able to find a lot of info on this. One or more of my pullies is really noisy.

What is the best way to test a pully? Does it need to be completely tight? No movement front/back or radially ?

When I removed the alternator for plug wires it made some noise when I spun it and squeaked a little. I can't spin it up at car speed by hand though.

Also my AC system belched oil over the belt and I'm sure everything connected. Don't know how bad this is for pully life.

So my questions are:

1. How much and what is normal pully movement.

2. Is oil bad on pulleys.

3. My AC compressor seal is bad/leaks. Would this cause a noise also?

The couple of times I took the serp belt off it looked ok I may get a new one though.

I'm definitely going to do headers soon. I tightened then up and it seems to have made it worse. I'm going to do this over Christmas probably. Not sure if long tube is what I want I have been looking at mid length headers. I'm pretty broke right now so any system that I can easily hook up to stock exhaust would be a plus until I can change that out. I'm more about making the car easier to work on then getting maximum HP.


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My alternator is definitely bad. My lights dim when I shift. On the plus side my new 02 sensor has raised my mileage. Before I was getting 12-17. Now I've ran 2 tanks and got 19 - 20


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Get a Delco alternator. Have the battery tested at auto parts store. Are you driving the car through the winter?

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Originally Posted by Dan

Get a Delco alternator. Have the battery tested at auto parts store. Are you driving the car through the winter?

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Yea it's my DD. I just replaced the battery. The alternator whines pretty bad and my lights dim when it's under a load.


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Alternator should be here tomorrow. I ordered a new one, not reman. Fiancé got me a new muffler for Christmas too. I ordered it online. Can save a lot using coupons and speedy perks. (She) got it for 70$ plus a 10$ giftcard. It's a magnaflow. Think it was 120$ retail. Too broke to upgrade whole exhaust right now :(

I've got a set of Goodyear eagle F1 GS-D3 tires on. It's what the car came with. Now that it is getting cold my ass end is sliding some when I turn! They must get hard. I don't like the tires they are pretty noisy. They run 300$ a pop. I'll need to find some winter tires.


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I'm back... Here is the short version

I've not done a lot to the car since my last post. The o2 sensor replacement and new alternator didn't fix the car 100%, but did bring my mileage up from 180 to at most 280 miles per tank. I was happy with this until a few months ago when the tick noises got worse. Over the last few days I have chased down a whining noise on the car.

• I replaced the tensioner assembly, AC system with a deleter pulley, and new belt.
• I used EEhack to log the car and its "tests" feature to note differences in strength between single cylinders.
• I fixed a low RPM jerk on clutch disengage by removing my #7 plugs metal boot that was arcing to block.
• I cleaned all grounds.
• Oil recently changed from dino to 0w-30 synthetic with K&N filter. This quieted noises somewhat.

Here is the long version in more detail.

I stopped work on the car after the alternator/02 sensor replacement last December. I started working on it the last month. Last night I removed all AC stuff and put in a new belt, tensioner, and AC delete pulley.

The Dorman AC delete bought from a chain using 94 camaro as a car is NOT a direct replacement. The one I bought was part #34209.

On the AC delete the holes were threaded for threads holding the compressor to the accessory mount piece. It won't work like that unless you have bolts with thread all the way. It also came with smaller bolts and spacers. I drilled out threads and had to shim the pulley outwards about 3/16" to get it in line with the other pulleys. It had a slight whir when I spun it, so I replaced the bearing grease with better stuff. I did this by prying off the cover on the ball bearing. Idk if this has any effect on the noise during engine speed/forces. This quieted it down to silent when spun by hand.

I installed the new belt after marking the old tensioner to measure how much stretch the old belt had. After that I installed the new tensioner and again marked it before I removed the compressor. I had a sneaking suspicion that the AC deleter had a bigger pulley. It was slightly bigger, I had to crank the tensioner almost all the way to get the belt on. Not sure what is considered normal on them.

Now that I've fixed these problems the car is a lot less noisy. The compressor was making the most noise. When its shaft seal failed it leaked oil onto all my accessories and opti. I think this caused all the bearings to fail to a degree. The car is now at 40,000 miles.

I downloaded EEhack and have been messing with it for datalogging. This is the first time I've logged it since changing out that o2 sensor. It says they have near equal peaks, lows, and average, but the left cross counts are a 25% lower vs. the right older o2.

My car was still riding rough and bucking at low RPM. It was very jerky when shifting. I saw sparks jumping off cylinder 7's metal boot again. I removed it and the problem went away. I used EEHacks cylinder balance test to see if any cylinders scored differently. Using this info I replaced plugs and checked connections on cylinders that were low. Now my car is running well. It feels faster than when I bought it.

Here are my next projects/upgrades. Some may be related I'm not sure :face_shocked:.

• So far the new belt/pulleys got rid of the faster high pitch tick. I could hear it driving at 1500-1700 and 2000-2200 RPM in the middle of the dash somewhat. I can hear other problems now that its quiet :laugh:.
• I now hear an electrical noise (verified not AIR) at all times most noticeable at idle. It follows electrical load more than engine RPM. Turning on the lights changes the noise a lot and stays changed after RPM stabilizes. This one is hard to search for. Most people are hearing the AIR.
• Since I've owned the car I replaced the battery and alternator with new non reman. The voltmeter is high (guessing 16-17v) at first start then goes down slowly. This doesn't always show up in data logs. Idk what voltage the PCM is showing.
• My low coolant light is still coming on but not frequent enough for me to think its broken. It happens after driving more than 1 hour. I noticed one night after I shut the car off, the hose going to the thermostat was sucked tight and flat. Still using the original 180 thermostat. I have a new 160.
• Going to sacrifice to the Camaro gods I can flash a tune to my PCM with EEhack. Flashing failed with Tunercats and the other flash program. It would get to 100% then shit on me. I would have to unplug the battery to start the car. I really want to change the fan speed and do some other simple things.
• When I removed the AC junk I noticed my water pump is black on the bottom :shiner:.
• I'm ordering a new water pump and maybe an optispark. The car idles worse on rainy days. I have an oscilloscope I built from a raspberry Pi. I will use that to check the high and low res signals first. Wish you could see them from datalogging.
• I'm showing a correction for rich conditions at idle and lean at high throttle. Not sure if this is normal.
• I can hear the lower pitched puff ticking sometimes. It sounds different then when I first start it and hear the piston slap. I should change the exhaust gaskets but will order long tubes if I go that far.

This is a long post. It's helped that I can read back on everything I was doing last year. I'm trying to document it closely in case I need it in the future.

Heres a datalog shot using EEhack. This was during a trip to my dads. Around 20 miles highway driving.
Attachment 37239
Im going to work on tuning and datalogs today while I have time.

Here's a shot of the removed AC partshttp://uploads.tapatalk-cdn.com/2016...71e37a37d5.jpg

There's actually an indicator line on the tensioner assembly, and a marked range that the indicator line is supposed to be within.

The AIR pump noise can be checked by unplugging the pump, or just waiting the 206 seconds typically required to enter closed loop, when the pump shuts off.

It's normal for the voltage regulator to kick the voltage up right after the engine has started, to replace the stored energy used to start the engine. But 17 V sounds a bit high. The voltage should taper down to ~13.5 V gradually. I just happened to be reviewing a Scan9495 log for someone. 12.0 V before the ignition turns to start, current inrush of the initial hit on the starter dropped it to 9.5 V. When engine starts, 14.1 V, drops to 13.5 V in five minutes. Power to PCM goes through the I/P fuse box, dash reads directly off the alternator. Not unusual for the PCM to read 0.5 to 1.0 V lower than the gauge.

"Normal" long term fuel trims want to be as close to 128 as possible. From my experience, anything between +/- 5% (121-135) is acceptable. Anything outside that range may indicate a problem.

I'll take a look at your screen shot, first to see what eeHack is capable of, then to see if any abvious problems.

EEhack is free to use with XDF files on http://fbodytech.com/ there are some guides and an automatic tune generator. I can't vouch for it, so use it at your own risk.

I found a few other screenshots of the cylinder "Tests" function. Other people have a low cylinder #1 number (whatever metric it is) so I'm not chasing that anymore. The number went slightly lower (worse) with a brand new wire and plug, who knows. It did help locating two cylinders with bad spark problems. My car smoothed out a lot since then it was a rough rider before :D.

I remember seeing a triangle on the tensioner but not the line, Ill have to look at it again. I drove around today and it ran well. It has been rainy the last two days so I can't hear/feel as well as normal.

The electrical noise I'm wondering if it may be my CCP. I can verify my noise is not a result of the AIR pump cycle at first start. It may be an AIR pump related part though. My noise is always happening no matter what. I ordered the water pump, spare chinese opti as a backup depending on how bad things are, and a gasket set.

Im holding off on my intake manifold leak until I can get new long tubes. If I'm tearing it apart again I'm going to do that too.