Now my car is acting up...need help
06-23-2009, 02:23 PM
#1
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Now my car is acting up...need help I have this posted in another forum as well:
Exact same problem my friend had last week with his 95 Z I'm now having with my 94 Z. I have a 1994 Z28, auto, under 78,000 miles. Two days ago Im getting on the freeway, as I hit the gas the car had no acceleration at all and was lacking power. I had to gradually apply gas to gain speed. When the car is cold its fine after it warms up a bit I cant punch on the gas anymore, just a little at a time.
So I took it to the dealership this mourning and they performed a few tests. This is what they said: They found no trouble codes. Fuel pressure was good. They test drove the car, back firing (which I never heard) and no power seemed like it has a plug catalytic converter.
They checked the exhaust back pressure and that passed test (it only had 1 psi but still in spec).
They recommended a leak down test for possible sticking valves (cost $270.00)! also recommended replacing spark plugs and wires.
So my question is which should I do first? Plugs and wires? catalytic converter? or this $270 leak test?
This could get expensive so I'm trying to narrow it down. Any help would be appreciated, thanks
Ronnie
Exact same problem my friend had last week with his 95 Z I'm now having with my 94 Z. I have a 1994 Z28, auto, under 78,000 miles. Two days ago Im getting on the freeway, as I hit the gas the car had no acceleration at all and was lacking power. I had to gradually apply gas to gain speed. When the car is cold its fine after it warms up a bit I cant punch on the gas anymore, just a little at a time.
So I took it to the dealership this mourning and they performed a few tests. This is what they said: They found no trouble codes. Fuel pressure was good. They test drove the car, back firing (which I never heard) and no power seemed like it has a plug catalytic converter.
They checked the exhaust back pressure and that passed test (it only had 1 psi but still in spec).
They recommended a leak down test for possible sticking valves (cost $270.00)! also recommended replacing spark plugs and wires.
So my question is which should I do first? Plugs and wires? catalytic converter? or this $270 leak test?
This could get expensive so I'm trying to narrow it down. Any help would be appreciated, thanks
Ronnie
06-23-2009, 03:52 PM
#2
What I would do is:
Replace in the following order for the ignition...plugs, wires, coil, opti, ICM.
Test the fuel pressure yourself and see what you get, replacing the fuel filter never hurts.
Removing the y-pipe is simple, do that and see if anthing changes.
Try unplugging your MAF and o2's and disconnect the vacuum line from your EGR and drive the car around and see if anything changes.
Report back with your findings.
Replace in the following order for the ignition...plugs, wires, coil, opti, ICM.
Test the fuel pressure yourself and see what you get, replacing the fuel filter never hurts.
Removing the y-pipe is simple, do that and see if anthing changes.
Try unplugging your MAF and o2's and disconnect the vacuum line from your EGR and drive the car around and see if anything changes.
Report back with your findings.
06-23-2009, 04:06 PM
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Launching!
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What I would do is:
Replace in the following order for the ignition...plugs, wires, coil, opti, ICM.
Test the fuel pressure yourself and see what you get, replacing the fuel filter never hurts.
Removing the y-pipe is simple, do that and see if anthing changes.
Try unplugging your MAF and o2's and disconnect the vacuum line from your EGR and drive the car around and see if anything changes.
Report back with your findings.
Replace in the following order for the ignition...plugs, wires, coil, opti, ICM.
Test the fuel pressure yourself and see what you get, replacing the fuel filter never hurts.
Removing the y-pipe is simple, do that and see if anthing changes.
Try unplugging your MAF and o2's and disconnect the vacuum line from your EGR and drive the car around and see if anything changes.
Report back with your findings.
06-23-2009, 04:35 PM
#4
What I do is pop the plug socket onto the plug, then pop the 3" ext on, then put on the wrench, works well, and you have to do a lot of it by feel, not sight.
06-23-2009, 05:31 PM
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driver side you could do from the bottom prity easy. passanger side you could do the 1st 3 from the top and depending how big ur hands are you would need to remove the starter and do the last one from the bottom.
06-23-2009, 05:57 PM
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Thanks for the tips guys...i think Ill start tomorrow on it.
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06-24-2009, 01:37 PM
#8
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How easy would it be to replace the ICm and coil?
06-24-2009, 02:16 PM
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Very easy, coil is not too expensive, the ICM, however, is like 80 bucks IIRC. I would recommend that you only use GM parts for both, don't use Autozone crap for vital sensors, etc. Plugs and wires are more difficult but shouldn't take you more than 30 mins after you've done them a few times. They are also more likely to be the cause of problems.
06-24-2009, 02:41 PM
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Very easy, coil is not too expensive, the ICM, however, is like 80 bucks IIRC. I would recommend that you only use GM parts for both, don't use Autozone crap for vital sensors, etc. Plugs and wires are more difficult but shouldn't take you more than 30 mins after you've done them a few times. They are also more likely to be the cause of problems.
As far as plugs go Im sticking eith the AC Delco plugs (RapidFire) hope those are the right ones...second what wires should I get? I was thinking of the MSD (part number 32149) for my 94 Z28 but, I also saw some cheaper Tylor wires not sure which ones to get.
06-24-2009, 03:14 PM
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Most dealer "techs" are morons and should not be believed as to what tests they did and what they recommend. I highly doubt they put load on the engine to see what fuel pressure was doing. A bad fuel pump can still produce the adequate PSI with the engine at idle or even free revving. What you need to do is buy yourself a fuel pressure gauge, put it on the Schrader valve, make it so you can see the pressure while driving, take the vacuum off the fuel pressure regulator (so the pump is sending a consistent 42 to 45psi) and punch it to put load on the engine and see what your fuel pressure gauge does. If it dips at all then your pump needs to be replaced.
This is one of the cheaper and easier tests to do and besides you should have a fuel pressure gauge amongst your tool collection anyhow...
It would also be a good idea to scan the PCM to see what the 02 sensor is doing...
One other thing I might add...
Having the same symptoms as you I discovered my water pump was leaking, however it would not do so until the coolant system was pressurized. This would cause it to leak onto the opti and I would then have ignition issues. Check to make sure your water pump is not leaking.
This is one of the cheaper and easier tests to do and besides you should have a fuel pressure gauge amongst your tool collection anyhow...
It would also be a good idea to scan the PCM to see what the 02 sensor is doing...
One other thing I might add...
Having the same symptoms as you I discovered my water pump was leaking, however it would not do so until the coolant system was pressurized. This would cause it to leak onto the opti and I would then have ignition issues. Check to make sure your water pump is not leaking.
Last edited by SS RRR; 06-24-2009 at 03:21 PM.
06-24-2009, 03:58 PM
#12
Your right im going to man up and replace the plugs and wires first. Hopefully thats the answer. I just hate the thought of doing the work and thats not the problem.
As far as plugs go Im sticking eith the AC Delco plugs (RapidFire) hope those are the right ones...second what wires should I get? I was thinking of the MSD (part number 32149) for my 94 Z28 but, I also saw some cheaper Tylor wires not sure which ones to get.
As far as plugs go Im sticking eith the AC Delco plugs (RapidFire) hope those are the right ones...second what wires should I get? I was thinking of the MSD (part number 32149) for my 94 Z28 but, I also saw some cheaper Tylor wires not sure which ones to get.
06-24-2009, 07:20 PM
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One other thing I might add...
Having the same symptoms as you I discovered my water pump was leaking, however it would not do so until the coolant system was pressurized. This would cause it to leak onto the opti and I would then have ignition issues. Check to make sure your water pump is not leaking.
Having the same symptoms as you I discovered my water pump was leaking, however it would not do so until the coolant system was pressurized. This would cause it to leak onto the opti and I would then have ignition issues. Check to make sure your water pump is not leaking.
06-24-2009, 08:18 PM
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i had the same problem mine was the cat stopping up.. it got to where it would do it time i crunk it up... i would try unbolting the y pipe from the cat and pull them apart and fire it up and see if it helps.. good luck
06-26-2009, 06:17 PM
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Yea i think that maybe it could be your o2 sensor or maf... maybe someone eals will chime in and correct me if im wrong but i think when you first turn your car on while its cold it runs in i think it open loop? Anyways i think that the car does not take readings until the car warms everything up.. so if your cars only doing it after it warms up id check that stuff. and i think that if your o2 was not totally out you would not throw any codes, so you would have to have a dealership to read them.... ok never mind you took it to the dealer... anyways that’s why i would check the stuff i said above
