Another new ZR1 owner
07-22-2011, 10:01 PM
#1
Le Mans Master
Thread Starter
Another new ZR1 owner
Just picked up my first ZR1 and like 10th Vette off of the forum. It's a 90 with 77k and she needs glitch type stuff that I could use some advise from those familiar with the LT5 as I have pretty much all the LT1 and L98 experience. She throws an Ecm code 33 for low map sensor pressure, where is the Map on this thing? Second the secondary air pump under the pass headlight growls when I turn the key, and then on occasion with the key car off on this coupled with fact that sometimes it takes forever for her to idle down from 1500 rpm tells me there is a vacuum leak somewhere, where does the vacuum line that comes from the pump go? it disapears under the Plenum. I don't hear any hissing so any ideas where I should look or look for? It just got a new starter so the plenum was just off.
2nd when you let off the clutch to take off at low throttle it is unsmooth, Pressure plate? not alot of clutch work in my past.
A/C no workie compressor does not cycle on I'm not that great with a/c but it looks to have a newer compressor on it as it has crimps attaching the wires to the connector It has the conversion fittings, when I attached a can of freon the guage was way in the red I let some pressure out but still no cycling on by the compressor.
P.S. not that I need to but how in the world would you get the rear torx screw out of the pass side cam cover?
Thanks for the help guys.
2nd when you let off the clutch to take off at low throttle it is unsmooth, Pressure plate? not alot of clutch work in my past.
A/C no workie compressor does not cycle on I'm not that great with a/c but it looks to have a newer compressor on it as it has crimps attaching the wires to the connector It has the conversion fittings, when I attached a can of freon the guage was way in the red I let some pressure out but still no cycling on by the compressor.
P.S. not that I need to but how in the world would you get the rear torx screw out of the pass side cam cover?
Thanks for the help guys.
Last edited by Y-ME; 07-22-2011 at 10:05 PM.
07-22-2011, 10:07 PM
#2
Drifting
Join the ZR-1 registry, forum is free... ZR1.net
There is a map sensor behind the plenum under an aluminum plate
There is a 2nd under the ECM
The rough ride might be the map
the air pump creates vacuum and it will cycle when it first turns on....and when pressure drops every 30 seconds or so is probably acceptable......every 90 sec or more is more normal...possible vac leak under the plenum
trace the line to the rubber grommet that leads to a hard line that runs under the plenum, attach a vac hand pump and see if it holds
Most importantly join the Wazoo group in your area,....
There is a map sensor behind the plenum under an aluminum plate
There is a 2nd under the ECM
The rough ride might be the map
the air pump creates vacuum and it will cycle when it first turns on....and when pressure drops every 30 seconds or so is probably acceptable......every 90 sec or more is more normal...possible vac leak under the plenum
trace the line to the rubber grommet that leads to a hard line that runs under the plenum, attach a vac hand pump and see if it holds
Most importantly join the Wazoo group in your area,....
07-22-2011, 10:53 PM
#3
Le Mans Master
Thread Starter
Join the ZR-1 registry, forum is free... ZR1.net
There is a map sensor behind the plenum under an aluminum plate
There is a 2nd under the ECM
The rough ride might be the map
the air pump creates vacuum and it will cycle when it first turns on....and when pressure drops every 30 seconds or so is probably acceptable......every 90 sec or more is more normal...possible vac leak under the plenum
trace the line to the rubber grommet that leads to a hard line that runs under the plenum, attach a vac hand pump and see if it holds
Most importantly join the Wazoo group in your area,....
There is a map sensor behind the plenum under an aluminum plate
There is a 2nd under the ECM
The rough ride might be the map
the air pump creates vacuum and it will cycle when it first turns on....and when pressure drops every 30 seconds or so is probably acceptable......every 90 sec or more is more normal...possible vac leak under the plenum
trace the line to the rubber grommet that leads to a hard line that runs under the plenum, attach a vac hand pump and see if it holds
Most importantly join the Wazoo group in your area,....
What the heck is a Wazoo?
07-22-2011, 11:02 PM
#4
Drifting
group of guys that get together, and help fix each others Zs.....in your area I believe...they use a lift
seriously join the registry
If pump is going off every 5 seconds you have a vac leak
seriously join the registry
If pump is going off every 5 seconds you have a vac leak
07-22-2011, 11:45 PM
#7
Le Mans Master
Thread Starter
07-23-2011, 12:50 AM
#11
except that the registry forum is as free as this one....you're welcome
and yes the chip is working "normally" it's not "bad" just needs some updating. give mark haibeck an email at www.zr1specialist.com and get a new one made
and yes the chip is working "normally" it's not "bad" just needs some updating. give mark haibeck an email at www.zr1specialist.com and get a new one made
07-23-2011, 07:01 AM
#12
Burning Brakes
Member Since: Aug 2005
Location: Portsmouth VA
Posts: 1,050
Likes: 0
Received 0 Likes
on
0 Posts
except that the registry forum is as free as this one....you're welcome
and yes the chip is working "normally" it's not "bad" just needs some updating. give mark haibeck an email at www.zr1specialist.com and get a new one made
and yes the chip is working "normally" it's not "bad" just needs some updating. give mark haibeck an email at www.zr1specialist.com and get a new one made
Don't bounce the registry just yet either. Take a look around at the forums and make up your mind. They don't have ads plaster all over the place and do have to pay for the site. You get all kinds of ZR-1 gear and it's a family... way better than the usual CF crowd.
07-23-2011, 12:06 PM
#13
NCM Lifetime # 982
45 bucks ? Wow that's a lot of money. I could get a half tank of gas with that.
07-23-2011, 02:00 PM
#15
Team Owner
Member Since: Oct 2004
Location: altered state
Posts: 81,242
Received 3,043 Likes
on
2,602 Posts
St. Jude Donor '05
Just join the forum there its free youll find more answers on your Z there before here.. Just tryin to help.
-Former Z owner
-Former Z owner
Last edited by cv67; 07-24-2011 at 11:58 AM.
07-23-2011, 02:01 PM
#16
Team Owner
Member Since: Oct 2001
Location: Do or do not there is no try YODA
Posts: 23,121
Likes: 0
Received 296 Likes
on
141 Posts
The car could have an issue with the idle and a vacuum leak, but the idle return on the '90 in particular was a point of contention for owners. Return to normal idle could take as long as 30 seconds, and is completely normal, although it seems like forever after you have come to a complete stop. When you are still rolling a little bit, the idle will stay up some, as it does between shifts.
07-23-2011, 03:50 PM
#17
Pro
07-23-2011, 04:26 PM
#18
07-23-2011, 06:22 PM
#19
Safety Car
You can make a couple of tweaks in the chip to coax the target idle lower, which seems to reduce the 'idle hang' a little also. From what I understand, the early 91's and 90's had this condition especially bad...so that's normal, although it could be worse with a vacuum leak.
If you are idling at 1200, that's a leak, but if it runs at 800 or so in the morning after the initial speed settles, you're probably ok with all the hose connections. The throttle body can have a bit too much bypass air- mine did.
If you are idling at 1200, that's a leak, but if it runs at 800 or so in the morning after the initial speed settles, you're probably ok with all the hose connections. The throttle body can have a bit too much bypass air- mine did.
07-23-2011, 07:00 PM
#20
Burning Brakes
