Re: Exhaust changes causes problems
 

Just checked the car. Now the vaccum is not coming on when I turn the key. I know it was working before I took my drive. Any idea what happened. Is there an easy way to tie the secondaries open to check if this is the problem or if its just another problem?

When I turn the key the vaccum makes two little noises and then doesn't do anything.

Seems like I get one thing fixed and something else breaks. Anyone found any of that dynamite for me yet?

Re: Exhaust changes causes problems
 

where in Ga are you???

SGC is in thomasville and can take some headache away if you don't want to work on the car. one thing I found which can be embarrasing but it's common. if the injector wiring isn't clipped on securely they can pop off!!

you then have one or more secondary injectors that don't get any juice!

you can check for this by ohming out the injectors with the plenum still on

see

www.zr1specialist.com

for the procedure

the exh probably doesn't have anything to do with it, as mentioned above it's just letting you hear what you didn't before, and if you were a bit lean before, you are a bit leaner now!!

the stock chip should work fine. definitely need to change that other 02. one new and one old isn't a good idea, they are hard to get to. just another reason to put those headers on!

good luck. my bet is that you have a bad plug wire or coil pack. fairly common.

you can test that by pulling one plug wire at a time and putting a grounded plug in the wire. when you see a weak spark, you typically found out which is misfiring.

pull the plugs and have a good look at them, they reveal alot. if the injectors are leaky (probably not) you can often smell it from that cyl with the plug out.

the lt5 isn't that tough to work on, just be patient and get the factory service manual to keep you on track. has some great troubleshooting flowcharts that really help.

Re: Exhaust changes causes problems
 

roger ,there is a fuse on the driver side of the car just in front of the brake master cylinder on the inside of the wheel well its a 10 amp its for the vaccume pump. it may be blown as mine was

Re: Exhaust changes causes problems
 

Ok, checked the inline fuse, it was fine. Is there anything else I should check electrically for the vacuum pump.

Again, when I turn the key the pump now clicks twice. Before it use to run for a couple of minutes.

Re: Exhaust changes causes problems
 

Pull the vacuum hose off at the bottom of the pump. But your problem does not lie here. Take one thing at a time.

Roger, I'll give you a shout in a few.

Re: Exhaust changes causes problems
 

What do I need to do next. I drove the car tonight and it drove pretty good. I don't hear the vacuum when I turn the key, but it sure seems like the secondaries are working.

Re: Exhaust changes causes problems
 

roger ,pull the connection off the vaccume pump then go and turn on the ignition and listen for the pump to turn on . if it doesnt run all the time with the hose off it could have a problem. here is where i have a tough time i dont know how to show you the link on that stuff . i can bearly type . on corvette action center in the zr1 area is a good thread on the secondary system and the vACCUME PUMP TOO. hope nthis help s going to get busy . grass is getting ready to grow , have to paint the new house after work . wife a has found a new toy this foam that is so light you cant feel it till it oooozes out of things like gloves hats shoes . i gotta be the only married guy in the world whose pregant wife turned into the biggest prankster ever born. sure is fun:o

Re: Exhaust changes causes problems
 

Brad, I checked the vacuum pump and it turns out it is working fine.

I talked with Jeff and he thinks it could be a few things. I am going to try and elimenate them one by one.

Sounds like you are going to be a busy man pretty soon. Your wife sounds like quite a gal. I guess you have to watch everything you put on, or it might have a suprise in it.:mrgreen:

Re: Exhaust changes causes problems
 

I had a few of the same symptoms and guess what; it turned out one of the crappy rachet plastic clamps came off a fuel pump hose allowing fuel to be pumped around the tank instead of to the injectors. Replaced plastic clamps with stainless clamps and all was well. Just another possibility.

Re: Exhaust changes causes problems
 

Just got back from about a two hour drive in the Z. The car didn't stumble at all during WOT. :D

The Z still has a pretty good hesitation at lower rpms. The acid test, as Paul Workman put it, low rpms and floor it, my car stumbles every time.

Jeff did you get my pm with my address?

Re: Exhaust changes causes problems
 

Yep I did. ECM is on it's way monday.

Re: Exhaust changes causes problems
 

Just re-reading these posts. Sounds like a fuel issue to me but its not the fuel pump or filter. He has backfiring on decel and stumble at tip-in which sounds like a lack of AE. I would suspect TPS or CTS. My $.02.

Re: Exhaust changes causes problems
 

Jeff, just checking to see if you had a chance to send the ECM. I was hoping to possibly get the car running good before the Meeting in AL. I know it may not be the ECM, but it seems like the best place to start before I take the plenum off.

Re: Exhaust changes causes problems
 

Roger, it's supposed to be delivered tomorrow afternoon I believe.

Re: Exhaust changes causes problems
 

Thanks Jeff. I will let you know what happens when I hook it up. If it gets here tomorrow I will hook it up then. Thanks again for your help.

Re: Exhaust changes causes problems
 

No problem, hope to see you in Birmingham.

Re: Exhaust changes causes problems
 

Looks like Birmingham isn't going to happen for me.:thumbsdo:

I changed the ECM and there was no change. I appreciate your help Jeff, I will send the ECM back tomorrow.

With the ECM elimenated as the problem, looks like I will be going under the plenum for some answers.

What is my next step. I had new plugs put in in August, but I am not ruling that out. I have a set of spark plug cables to put on.

What gaskets do I need to get before I start?
What other things like maybe a coil pack or what else?

Again my car stumbles at low rpms. It has been driving better at WOT since I replaced the o2 sensors, but occasionally stumbles there as well.

If I don't figure this thing out before summer I will video the explosion.
(anyone found me a stick of dynamite yet):wink:

Re: Exhaust changes causes problems
 

What are the plugs gapped at?

Re: Exhaust changes causes problems
 

did you ever check the TPS ?

Does it have a smooth sweep up and down in volts?

Re: Exhaust changes causes problems
 

Roger,

Have you ever checked the fuel pump clamps like SGS suggested? Lgaff had a similar issue which was remedied by stainless hose clamps.
Or you keep talking about ambient temps affecting the performance.
Have you tried looking at the Coolant Temp Sensor and replacing?
The hesitation sounds like its going lean at tip in and for AE.
Again, a scantool would REALLY help here and save time/effort.

Re: Exhaust changes causes problems
 

I talked withy Jeff and looks like I will hopefully get him to look at the car while he is in Birmingham. As I told him, I have never worked on cars before. Looks like I picked a good vehicle to start with.:o

Hopefully I will have some good news after next weekend.

I appreciate everyones help!!! :worship:

Seems like everyone on the Registry is willing to help a brother of the beast out.

I am hoping soon to not be sooooo much trouble.

Re: Exhaust changes causes problems
 

sounds like bad spark plug to me
bj
91/1735

Re: Exhaust changes causes problems
 

I sure hope it is something that simple.

Re: Exhaust changes causes problems
 

happened to me(not with the z)....your favorite mechanic drops a plug on the floor,and still puts it in[-X
bj

Re: Exhaust changes causes problems
 

One more try...what are the plugs gapped at?

Re: Exhaust changes causes problems
 

I am sad to say I don't know. They are the Ac Delco plugs. The mechanic that put the in said they were the correct ones for the car, but right now that doesn't mean much to me.

Hope to find some answers next Friday.

Re: Exhaust changes causes problems
 

gm recommends .035'' for 90-92,and .050'' for 93-95...generally speaking,a smaller gap will give you easier starting while a wider gap is better for high speed...i would start with .035'',and go from there,keeping in mind that too wide a gap can cause misfiring,,,mine are set at .040''
91/1735

Re: Exhaust changes causes problems
 

Spark plugs are a cheap place to start.

I had a bad spark plug on the Z loosing pressure.
I started with the cheapest parts spark plugs.

And make sure you gap then .032- .035 i don't care what GM reccommands.

Pete

Re: Exhaust changes causes problems
 

One quick thing to look at - The vacuum hoses on the back of the plennum and on the fuel pressure regulator. If you had a slight back fire - they may have come off. Might contribute to your fuel issue.

Good Luck

D.Y. 91-#267
:)

Re: Exhaust changes causes problems
 

Issue resolved!!!!!

ALL HAIL JEFFVETTE.:worship: :worship: :worship: :worship: :worship:

I went to Birmingham to the vette gathering. Jeff was there helping Fred with his Zo6 race car and for the vette get together. After a long day driving the Zo6 on the track, Jeff took a couple of hours to help me with my car(I know he was tired). We were at Chris's house. (aka. Corvette95-Talk about a garage and car room. I hope Chris will post some pics of his garage, paint shop, basement room, and attick. Amazing). He was nice enough to allow us the use of his great garage. Anyway, long story short, problem turned out to be coil packs. Once again Jeff had anticipated this and brought the materials needed.

I have had the car since August 2007. Last night on my way home is the first time the car drove like it was supposed to drive. Man what a feeling!!!:D

I took a number of photos at the race track where Fred Turner and Jeff were taking turns in the zo6. I will post some when I figure out how to do it.

Again let me thank everyone for their input and help.

Jeff you are the man!!!!!

Re: Exhaust changes causes problems
 

Outstanding. I assume you will not be giving your car away now. LOL.
Congrats.

Re: Exhaust changes causes problems
 

Not going to blow her up now.:D

Now just looking forward to some more things I can do to the car, when I can afford it.

BTW. When I got my car it had a ground effects kit and wing(still does). You could tell Jeff was envious of my wing.:wink:

Re: Exhaust changes causes problems
 

glad the problem is fixed roger . no one has worked harder than you to try to find out what it was . it sure was nice of jeff to help you out . just goes to show what a great bunch of guy lurk here doing what ever they can to help those in need . sometimes it takes a person with jeff knowledge to fix our cars . he could fix them in his sleep i think. did ya buy him a pizza ? car is fun now huh?

Re: Exhaust changes causes problems
 

Yes, the car is a lot of fun now.

Jeff seemed to be more into Philly cheese steak than pizza.

Hope all is well with you and Deb.

Re: Exhaust changes causes problems
 

Roger, it was a pleasure meeting you and having you hang out for a bit. Fred really enjoyed giving you a ride at the track at speed and getting a feel for the track going. I think that high was only surpassed when you drove your car after the coil pack change.

Hope to see you at Petit in October.


Chris, thanks for the use of your garage and tools.

Re: Exhaust changes causes problems
 

Great to meet you, Roger (and Chris as well!). I cannot think of a more enjoyable weekend that I've had in a long time. I'm so happy for you that your Z is running as it should now! But we can't forget your quote after you took it out for a test drive once Jeff fixed you up: "Is it wrong to love another man?!?!" LOL! That made it all worthwhile, buddy! :D

BTW, I sure wish you could have stuck around to ride for a few more laps today. I know you had such a blast yesterday, (and it really made my weekend to hear you so excited about it!) but we just got goin yesterday when the checkered waved-- we weren't even up to speed yet! We'll have to reschedule you for another run sometime... Anyway, glad you can enjoy your Z now....good luck w/ the wing and ground effects! :D

Fred

Re: Exhaust changes causes problems
 

wow roger , 2 e ticket rides in one day , sounds like you had an awsome day .its nice to see a group of folk care so much .now if we could have that rub off on the world ..... oh well just a thought . i would have been scared to death in that race car. i can only do straight line .so auto crossing in your future ?those rides can get ya hooked:)

Re: Exhaust changes causes problems
 

i would have been scared to death in that race car.


I wasn't scared.:jawdrop:

Who am I kidding heck yes I was scared in that race car.:o Like Fred said the tires hadn't gotten a chance to even heat up and I was screaming like a girl. There is one turn where you come over a hill moving right, I don't know how fast we were going, all I know is we were moving laterally as well as forward and Fred never got off of the gas. This was the turn where a guy dumped his Porche turbo.

It was great. Way too expensive a hoby for me right now though.

Fred gave me a new appreciation for REAL driving.:worship:

I hate I had to end my weekend short late on Saturday.(sick kid at home)

I look foreward to anymore events that gets guys like this together.

Man it was fun.:D

Re: Exhaust changes causes problems
 

I read this whole freakin thread and the guy with the problem never told us what it was[-X

Re: Exhaust changes causes problems
 

The problem was clearly the exhaust I sold him.:D