Plenum pull veterans I have Q's

[tomtom72]

Hi all, First let me thank all the senior members who have provided info for pleebs like me to study at this site and the regional sites. Thanks so much! The members make this car fun to own.

I have three common issues I'm going to try to address. Breather oil leaks, secondary throttle vacuum leak and a few bad injector coils. I have a Helm for my 90 and most all of the parts. Easier to list what I didn't buy: DIS module, starter, alt., linkage parts for 2* butterflies, CTS, fan switch and mounting plate for coils. I think I'll buy the two sensors as soon as I eye the connection on the CTS.

Q1: It looks like there is enough room to just move the A/C comp. enough to get at the breather cover bolts without discharging the A/C gas?

Q2: To do breather gasket leak the inj. housings should be R & R'ed because all that is in the way?

Q3: P/S pump doesn't have to come out to move A/C comp.?

Q4: Helm doesn't say T/B & Air horn extension & plenum & Inj. H. bolts need loctite, I missed it in reading the book?

Q5: Parts CD says there are different style connectors on CTS for 90 Z, I read this worng?

Q6: To change injectors the fuel rails should be separated from the distribution block by disconnecting the lines at the rails? And those O-rings are the same as for the fuel filter?

Sorry for taking up space! I never worked on FI before now. Got me some rented work space for a month so I gotta get straight before I start to disassemble anything. I'm sure I overlooked something. If so, shout at me!

Thanks,
Tom
As a P.S. to all this I just noticed someone else's post about injectors. I purchased RC #205 and it seems I got the wrong ones? It seems I should have bought #225? Any help on this would be great! Thanks again.

[haber rj]

Hello Tom, I am also in the process of replacing all my injectors and with the modification that I have done ( bolt ons, headers, corsa exhaust, new prom) they told me to run 24lb or 257cc injectors. I am not familiar with replacing injectors or the removal of the plenum, but I guess that there is no time like now to get in and learn. It really doesn't look that difficult, taking the upper plenum off should be ok if I take my time.

haber nj

[tomtom72]

Hi haber rj, Yea I guess we all gotta start learning at some point! Did you check out Jeffvette's Pacfic NorthWest web site? It has some great step by step lay outs of the plenum pull.
Good luck with your project!!

Tom

Originally Posted by haber rj

Hello Tom, I am also in the process of replacing all my injectors and with the modification that I have done ( bolt ons, headers, corsa exhaust, new prom) they told me to run 24lb or 257cc injectors. I am not familiar with replacing injectors or the removal of the plenum, but I guess that there is no time like now to get in and learn. It really doesn't look that difficult, taking the upper plenum off should be ok if I take my time.

haber nj

As I replied in Tom's post, the 205's will be fine. With bolt on's, headers and even porting the 205's will be fine.

Tom thanks for the plug on my site. It's www.pnwzr1.net The tear down info is in the tech section.

[tomtom72]

Jeffvette, and

I'm now a little more at ease with this. Your site should be required reading for all rookie owners along with the stuff on the NetRegistry!

Thanks on the injector Q also! I was thinking if I can't even order parts correctly what am I doing taking the plenum off. I feel better hearing the voices of experience. I would sent the stuff to you but I don't know yet how long my Uncle will like his S500 Merc sitting out side
I told him can I have two weeks & he didn't seem to mind. I don't want to push my luck. I guess a little 600 wet and LPE's paint plus maybe some clear & a little 3000 wet will have to do this time.

Thank you for responding & helping me out!

Tom

Not a problem Tom. And depending on the color you choose, I could get it done quickly. Not like another week would kill your uncles Merc.

[tomtom72]

Jeff,
I'm not brave enough to try to remove the cam covers!
Besides the budget took a big hit with all the parts I bought. I'm gonna go get the two sensors and I may try to rebuild the starter & alt. The jury's still out on the DIS module. All the vacuum parts, coils, magnecor wires, 16 injectors, gaskets and breather box stuff.

I guess you can tell I don't want to go back under there any time soon! Besides I have to save $ for gas for next season because I have alot of places I want to go with the Z.
Tom

[Z Factor]

Originally Posted by haber rj

Hello Tom, I am also in the process of replacing all my injectors and with the modification that I have done ( bolt ons, headers, corsa exhaust, new prom) they told me to run 24lb or 257cc injectors. I am not familiar with replacing injectors or the removal of the plenum, but I guess that there is no time like now to get in and learn. It really doesn't look that difficult, taking the upper plenum off should be ok if I take my time.

haber nj

Hello, and welcome to the forum.

I would say that "24lb or 257cc injectors" might be a bit much considering the stock injectors run 220cc/min. I will be addressing Toms question on the matter, and a response or two he has gotten, but in the mean time, reconsider going up to that injector unless there is a sound logical reason to do so.

Originally Posted by tomtom72

Q1: It looks like there is enough room to just move the A/C comp. enough to get at the breather cover bolts without discharging the A/C gas?

There is enough slack/flex in the system that you can remove the AC compressor to get it off of the breather box and sitting down by the water pump with no issues.

Q2: To do breather gasket leak the inj. housings should be R & R'ed because all that is in the way?

No, the breather box should come out with out removing the injector housings (it does make it easier though). You will have to remove the secondary butterfly linkageand the actuators to get the breather box out.

Q3: P/S pump doesn't have to come out to move A/C comp.?

No, PS pump can stay put unless you are removing the driver side cam cover.

Q4: Helm doesn't say T/B & Air horn extension & plenum & Inj. H. bolts need loctite, I missed it in reading the book?

No loctite in any of the serviceable top end stuff.

Q5: Parts CD says there are different style connectors on CTS for 90 Z, I read this worng?

There are two different CTS sensors on the driver side injector housing. One is for the ECm reading, the other is for the gauge. To my knowledge these are the same for all years. One is a standard clip, the other is a spade connector.

Q6: To change injectors the fuel rails should be separated from the distribution block by disconnecting the lines at the rails? And those O-rings are the same as for the fuel filter?

Don't remember off the top of my head what the size for the fuel rail block is. I know you can either get them from GM or Kurt White.

As a P.S. to all this I just noticed someone else's post about injectors. I purchased RC #205 and it seems I got the wrong ones? It seems I should have bought #225? Any help on this would be great! Thanks again.

The 205's will be fine. 225's are recomended for larger motors or Nitrous applications.

[Z Factor]

Originally Posted by tomtom72

As a P.S. to all this I just noticed someone else's post about injectors. I purchased RC #205 and it seems I got the wrong ones? It seems I should have bought #225? Any help on this would be great! Thanks again.

You were probably referring to my recommendation about getting the 225cc/min injectors vs. the 205's that you ordered. As Jeff posted, the 205's will be fine for your application, as would the 225's and will not cause any harm. Both have been used by different ZR-1 owners, and it is a matter of splitting hairs as to which is better. Some people actually use the 205's for primaries, and the 225's for the secondaries. Flow rates vary for several reasons, not the least of which is based on the amount of pressure when measuring them. RC uses 43.1psi (if memory serves me correctly) to bench injectors. If you use greater psi, it will have an effect on the final numbers. Strictly speaking, using GM's numbers, the correct injector by RC will be their 225cc/min which is closer to the stock 220cc/min or 21lb injector, which RC would confirm if you were to contact them. However, that is not to say that a 19lb injector which flows at 205 (psi being equal) will starve the engine of fuel. As Jeff said, if you were to mod your LT5 then having the 225's would make sense, so anyone considering that in the future may as well go with the 225's now.

I hope that helps to also ease your mind since I did not want you to be concerned based on my other post. I should have explained it in more detail so there would not be any misunderstandings.