car pulsates under load when in power mode

[Mahogaraunch]

Originally Posted by zr1man@yahoo.ca

I just bought a 1991 corvette zr1 and i dont find any difference when i switch from normal to power mode. in normal mode the car drives fine. when i switch to power mode, the light comes on. car still feels like 210 hp and when i accelerate heavy, the car pulsates and vibrates. when i let off and drive normal, the pulsation goes away.

im thinking its the secondary injectors that may be the problem as i continue to read in the other posts.

I would like to be sure before i invest in them. Also, if it is the injectors, is there anybody you can recommend with a decent price? Im from Canada if that makes a difference. Maybe the local parts shop can order from a major supplier.

sorry, one last thing... any advice or tricks to do an oil change? and is it true the zr1 takes 12 litres?

thanks in advance!

I have the exact problem with mine! I have a 1990 ZR1 with 11,000km on it which was recently brought up from Florida. Needless to say, I got it out on the road after a long Ontario winter to find under the normal load the car drives perfectly. Under full power, the car shudders and there is no performance difference.

I have it going in this Monday for service, but I am not confident my garage has worked on a ZR1 before. What does anyone think the repair price for the injectors may run me? Does anyone have reservations about bringing a ZR1 to any garage? I am near the Peterborough area and am unaware of Corvette service shops in the area.

Thanks for the input.

[1990 415]

Originally Posted by Mahogaraunch

I have the exact problem with mine! I have a 1990 ZR1 with 11,000km on it which was recently brought up from Florida. Needless to say, I got it out on the road after a long Ontario winter to find under the normal load the car drives perfectly. Under full power, the car shudders and there is no performance difference.

I have it going in this Monday for service, but I am not confident my garage has worked on a ZR1 before. What does anyone think the repair price for the injectors may run me? Does anyone have reservations about bringing a ZR1 to any garage? I am near the Peterborough area and am unaware of Corvette service shops in the area.

Thanks for the input.

Have you asked this garage if they have ever worked on an LT5? Very unlikely they have. They will very likely make you wish you never took it to them. Only let an LT5 knowledgible person work on your ZR-1. Injector replacement isn't difficult to do yourself. Getting that first plenum pull under your belt is the key to really feeling like you are a brother of the beast. Don't let the inexperienced go near your LT5.

[jrd1990zr1]

Originally Posted by Mahogaraunch

I have the exact problem with mine! I have a 1990 ZR1 with 11,000km on it which was recently brought up from Florida. Needless to say, I got it out on the road after a long Ontario winter to find under the normal load the car drives perfectly. Under full power, the car shudders and there is no performance difference.

I have it going in this Monday for service, but I am not confident my garage has worked on a ZR1 before. What does anyone think the repair price for the injectors may run me? Does anyone have reservations about bringing a ZR1 to any garage? I am near the Peterborough area and am unaware of Corvette service shops in the area.

Thanks for the input.

Sounds like the same problem I had with my 1990 until I installed a set of new injectors.

FWIW, I wouldn't trust any non-GM dealer with a 1990 ZR1 (except the few specialists discussed by registry members). Likewise, there are very few GM dealers I would trust.

I recommend you check the injectors when the engine is hot to verify low resistance. Do the work yourself, there are a number of resources in the technical section.

Good luck

[zr1man@yahoo.ca]

Originally Posted by Mahogaraunch

I have the exact problem with mine! I have a 1990 ZR1 with 11,000km on it which was recently brought up from Florida. Needless to say, I got it out on the road after a long Ontario winter to find under the normal load the car drives perfectly. Under full power, the car shudders and there is no performance difference.

I have it going in this Monday for service, but I am not confident my garage has worked on a ZR1 before. What does anyone think the repair price for the injectors may run me? Does anyone have reservations about bringing a ZR1 to any garage? I am near the Peterborough area and am unaware of Corvette service shops in the area.

Thanks for the input.

Ive got a guy here in Bancroft (1hr away from Peterborough) that I trust to work on my ZR1 and going to use to help me re and re the plenum and install the injectors and coils. He is a perfectionist but not familiar with the lt-5. I think between this website for guidance and trouble shooting, and a skilled perfectionist like himself that I can use to help me do the install, we should be fine. Ill let you know how we make out with mine and if you want I can give you his number....he could come to Peterborough and give you a hand in your garage.

Also, in my travels i noted a Corvette specialty garage on the 401 somewhere between Oakville and cambridge...not sure where exactly but it was called Grand Sport Corvettes. Might be worth giving them a call and asking if they do service on lt5's.

[Mahogaraunch]

Originally Posted by zr1man@yahoo.ca

Ive got a guy here in Bancroft (1hr away from Peterborough) that I trust to work on my ZR1 and going to use to help me re and re the plenum and install the injectors and coils. He is a perfectionist but not familiar with the lt-5. I think between this website for guidance and trouble shooting, and a skilled perfectionist like himself that I can use to help me do the install, we should be fine. Ill let you know how we make out with mine and if you want I can give you his number....he could come to Peterborough and give you a hand in your garage.

Also, in my travels i noted a Corvette specialty garage on the 401 somewhere between Oakville and cambridge...not sure where exactly but it was called Grand Sport Corvettes. Might be worth giving them a call and asking if they do service on lt5's.

I noticed when you quoted the part # from Summit for the secondaries, that the part appeared to be primaries only. I called Summit and the only secondaries they stated they had were for $180 per injector. Not sure if this part you quoted would work as secondaries?

Sorry guys, im not a handy tech guy like you all seem, and doing this job myself is out of my league by a long stretch. The references to Ohm's do confuse me. I have a good rapport with my garage in town but they have not worked on an LT5 before. I'm really not sure where to turn next as I brought the car to the garage and had the fuel filter replaced, the throttle body cleaned, and some injector cleaner placed in the tank. They thought if I drove it for a bit it would correct the problem. I took it out for a drive but as the weather has been crap have not had an opportunity to really drive it. I can hear the vaccuum pump running for several seconds when I turn the key to the accessory position, so that would not appear to be the problem.

Not sure if I want to invest $1400 for a set of 8 secondaries plus however long it takes the garage to install it without knowing for sure thats my problem with the car. With everything I read on this board I am confident the secondaries are my problem, but just not 100% sure.

Thanks for any input you guys have.

[jrd1990zr1]

Originally Posted by Mahogaraunch

I noticed when you quoted the part # from Summit for the secondaries, that the part appeared to be primaries only. I called Summit and the only secondaries they stated they had were for $180 per injector. Not sure if this part you quoted would work as secondaries?

Sorry guys, im not a handy tech guy like you all seem, and doing this job myself is out of my league by a long stretch. The references to Ohm's do confuse me. I have a good rapport with my garage in town but they have not worked on an LT5 before. I'm really not sure where to turn next as I brought the car to the garage and had the fuel filter replaced, the throttle body cleaned, and some injector cleaner placed in the tank. They thought if I drove it for a bit it would correct the problem. I took it out for a drive but as the weather has been crap have not had an opportunity to really drive it. I can hear the vaccuum pump running for several seconds when I turn the key to the accessory position, so that would not appear to be the problem.

Not sure if I want to invest $1400 for a set of 8 secondaries plus however long it takes the garage to install it without knowing for sure thats my problem with the car. With everything I read on this board I am confident the secondaries are my problem, but just not 100% sure.

Thanks for any input you guys have.

I had similar problems with both my 1990s. Was bad secondary injectors caused by the E10 in gas.

FWIW, I bought a set of 16 injectors from Jon Banner (Fuel Injector Connection) for under $400. http://fuelinjectorconnection.com/shop/

http://www.corvetteinjectors.com/sho....php?groupid=3

Replaced them myself. I am definately not a tech guy. This was the first time I ever tried to do a repair such as this. If you use the instructions here on the registry and have a new set of primary o-rings and a spare set of plenum gaskets from Jerry's gaskets the job isn't that difficult. http://jerrysgaskets.com/store2/root/

Just make sure to drain the coolant down enough and use the procedure to refill coolant. This is probabily the most difficult part.

[zr1man@yahoo.ca]

Originally Posted by Mahogaraunch

I noticed when you quoted the part # from Summit for the secondaries, that the part appeared to be primaries only. I called Summit and the only secondaries they stated they had were for $180 per injector. Not sure if this part you quoted would work as secondaries?

Sorry guys, im not a handy tech guy like you all seem, and doing this job myself is out of my league by a long stretch. The references to Ohm's do confuse me. I have a good rapport with my garage in town but they have not worked on an LT5 before. I'm really not sure where to turn next as I brought the car to the garage and had the fuel filter replaced, the throttle body cleaned, and some injector cleaner placed in the tank. They thought if I drove it for a bit it would correct the problem. I took it out for a drive but as the weather has been crap have not had an opportunity to really drive it. I can hear the vaccuum pump running for several seconds when I turn the key to the accessory position, so that would not appear to be the problem.

Not sure if I want to invest $1400 for a set of 8 secondaries plus however long it takes the garage to install it without knowing for sure thats my problem with the car. With everything I read on this board I am confident the secondaries are my problem, but just not 100% sure.

Thanks for any input you guys have.

now you have me wondering if i bought the right injectors from summit racing? i got the part number from this reference by a zr1 specialist.
http://www.zr1specialist.com/HAT%20W...eplacement.pdf

he states that accel 150821 is a dirrect fit for the 91 zr1 and he uses this brand often on customers vehicles.

Can anybody confirm if purchased the right injectors for my secondary injectors? acc-150821 8-pack 21 lb/hr $300 from summit.

[lbszr]

Originally Posted by zr1man@yahoo.ca

http://www.zr1specialist.com/HAT%20W...eplacement.pdf

he states that accel 150821 is a dirrect fit for the 91 zr1 and he uses this brand often on customers vehicles.

Can anybody confirm if purchased the right injectors for my secondary injectors? acc-150821 8-pack 21 lb/hr $300 from summit.

That website is as good as the factory maintance manual. Looks like the same as 150121, only packaged with 8 and saves a little money.

[Mahogaraunch]

Well, just ordered a set of 16 from Corvetteinjectors and the gasket set from jerry'sgaskets..

Anything else I need that anyone can think of? Spoke to my shop and they quoted about 3.5 hours to do the job.

Thanks.

[lbszr]

Originally Posted by Mahogaraunch

I noticed when you quoted the part # from Summit for the secondaries, that the part appeared to be primaries only. I called Summit and the only secondaries they stated they had were for $180 per injector. Not sure if this part you quoted would work as secondaries?
Thanks for any input you guys have.

I don't know which ones those are, but 150121 $40 each from summit 21# is what I used for prim. and sec. 8 Of them need a plastic tab removed so the electical connector will plug in, forget whether it was sec. or pri.

I would have to look, but I thought mine were yellow though.