Checked my injectors today and... - ZR-1 Net Registry Forums

Matt B · 03-20-2021

they appear to be great! I measured the resistance following Marc's guide. Unfortunately it was merely 30 degree outside but all 16 showed readings between 11.8 and 12.1 ohm. Not sure if that result holds true once the engine is hot but I can't test a hot engine at the moment. So, fairly okay results for the time being I would say.

Her injectors were replaced back in 2010 (according to Carfax) by a Chevrolet dealership. So I assume they used stock injectors replacement. However as she was only driven 1000 miles since then the fuel apparently has not caused major damage.

After the decomposed left cat insert this is good news!

Does anyone know whether GM maybe used the later version to replace worn early injectors?

secondchance · 03-20-2021

Quote:

Originally Posted by Matt B

they appear to be great! I measured the resistance following Marc's guide. Unfortunately it was merely 30 degree outside but all 16 showed readings between 11.8 and 12.1 ohm. Not sure if that result holds true once the engine is hot but I can't test a hot engine at the moment. So, fairly okay results for the time being I would say.

Her injectors were replaced back in 2010 (according to Carfax) by a Chevrolet dealership. So I assume they used stock injectors replacement. However as she was only driven 1000 miles since then the fuel apparently has not caused major damage.

After the decomposed left cat insert this is good news!

Does anyone know whether GM maybe used the later version to replace worn early injectors?

I wouldn?t put too much faith in later OEM injectors either. My 94 injectors went bad before I bought it. Took me 9 years to figure out why she wasn?t running quite right.

wfot · 03-20-2021

I have full set of ACCEL injectors for sale. just drop them in. all 16, 8 have the secondary tabs removed already, they are 21lb, have about 5,000 miles on them. $500.00 here is the link:

https://www.zr1.net/forum/showthread.php?t=32652

thanks John

XfireZ51 · 03-20-2021

Test the injectors using a heat soak. Run the motor to operating temps(preferably driven)then shut engine off. Allow heat soak for 30min. then check resistance. See if u get something different.

Paul Workman · 03-21-2021

Quote:

Originally Posted by XfireZ51

Test the injectors using a heat soak. Run the motor to operating temps(preferably driven)then shut engine off. Allow heat soak for 30min. then check resistance. See if u get something different.

Yup! Heat soaking to ferret out an electrical windings issue is NOT unique to injectors either! Coils of all sorts often fail once they are heated up. In my personal experience: ignition coils, injectors, generators, amplidynes (there's a device ya don't often see!), etc. ALL have demonstrated failure, but only AFTER heat soaking.

(The insulation of the coil windings breaks down with age and heat cycles. The windings flex, i.e., the coil wire loops expand and contract and scrub against each other until the insulation sloughs off and the wire loops begin shorting. This is why the resistance goes down when the (injectors) are heated - the path trough the coil wire loops is shorted and thus less wire traveled = less resistance! Just some trivia I learned under duress, back in my gun and missile fire control dayz!)

1991 Corvette ZR-1 · 03-21-2021

Quote:

Originally Posted by secondchance

I wouldn?t put too much faith in later OEM injectors either. My 94 injectors went bad before I bought it. Took me 9 years to figure out why she wasn?t running quite right.

Oof! That?s rough. Marc?s method for checking the injectors was great. I ended up sending him some beer money for that one once it helped me find a bad injector. Mine was a double whammy. I also had a bad actuator for my passenger side bank of secondaries. Paul Workman to the rescue on that part.

WARP TEN · 03-22-2021

Quote:

Originally Posted by 1991 Corvette ZR-1

Oof! That?s rough. Marc?s method for checking the injectors was great. I ended up sending him some beer money for that one once it helped me find a bad injector. Mine was a double whammy. I also had a bad actuator for my passenger side bank of secondaries. Paul Workman to the rescue on that part.

Always glad to hear how our great long time members help out. One of the special things about this group. --Bob

Matt B · 03-22-2021

Thanks all for your answers. Currently I can't start the engine as Phil's replacement cam sensor it still traveling

. But will follow the advise and test it hot asap.
Thanks also for offering the Accel injectors. I tend to get a FIC set from Jerry, maybe also stock them as spare reserve. Might come in handy one day.

ZR2 · 03-27-2021

I replaced all 16 injectors on a previous 91 I had and did it with the FIC injectors and couldnt have been happier. Straight drop in, A few years ago I tripped across a 94 that needed saving. Since in my youth I hurt a few cars I am trying to save cars instead. The 94 developed a mis last summer, so as the saying goes while in there. I replaced the injectors with a fresh set of FIC ones. They are a quality piece from what my limited experience can tell.

03-20-2021	#1
Matt B Join Date: Jan 2021 Location: Beautiful Bavaria Posts: 522	Checked my injectors today and... they appear to be great! I measured the resistance following Marc's guide. Unfortunately it was merely 30 degree outside but all 16 showed readings between 11.8 and 12.1 ohm. Not sure if that result holds true once the engine is hot but I can't test a hot engine at the moment. So, fairly okay results for the time being I would say. Her injectors were replaced back in 2010 (according to Carfax) by a Chevrolet dealership. So I assume they used stock injectors replacement. However as she was only driven 1000 miles since then the fuel apparently has not caused major damage. After the decomposed left cat insert this is good news! Does anyone know whether GM maybe used the later version to replace worn early injectors? __________________ ZR-1 #638/1991

03-20-2021	#3
wfot Join Date: Jan 2009 Location: New jersey Posts: 154	Re: Checked my injectors today and... I have full set of ACCEL injectors for sale. just drop them in. all 16, 8 have the secondary tabs removed already, they are 21lb, have about 5,000 miles on them. $500.00 here is the link: https://www.zr1.net/forum/showthread.php?t=32652 thanks John

03-20-2021	#4
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,685	Re: Checked my injectors today and... Test the injectors using a heat soak. Run the motor to operating temps(preferably driven)then shut engine off. Allow heat soak for 30min. then check resistance. See if u get something different.

03-22-2021	#8
Matt B Join Date: Jan 2021 Location: Beautiful Bavaria Posts: 522	Re: Checked my injectors today and... Thanks all for your answers. Currently I can't start the engine as Phil's replacement cam sensor it still traveling . But will follow the advise and test it hot asap. Thanks also for offering the Accel injectors. I tend to get a FIC set from Jerry, maybe also stock them as spare reserve. Might come in handy one day. __________________ ZR-1 #638/1991

03-27-2021	#9
ZR2 Join Date: Jun 2018 Location: Maryland Posts: 53	Re: Checked my injectors today and... I replaced all 16 injectors on a previous 91 I had and did it with the FIC injectors and couldnt have been happier. Straight drop in, A few years ago I tripped across a 94 that needed saving. Since in my youth I hurt a few cars I am trying to save cars instead. The 94 developed a mis last summer, so as the saying goes while in there. I replaced the injectors with a fresh set of FIC ones. They are a quality piece from what my limited experience can tell.