Sudden misfire after restart - ZR-1 Net Registry Forums

tccrab · 08-20-2006

Took my oldest son out for a 20 mile or so ride in Girlfriend this afternoon.
Started and ran fine just like always.
Stopped by a buddy's house for 30 mins or so, then fired her up to go home. Started fine but as soon as I pulled out of the driveway it was obviously missing on at least 2 cylinders.
At idle you can hear the dual mass flywheel rattle.

Babied her home, seems to be ok at cruising speed, just low RPM's she's missing badly. On the way back home it seemed to run just a little hotter than usual, but never anywhere near the danger zone. After letting her cool off for about three beers I checked all the easy things, the hoses (map sensor hose first), spark plug wires, etc.
No luck there, everything seems OK.

Don't smell gas at the tailpipe so it's not mechanical.
Tomorrow I'll dig out the Helms books, get my tools out, pull the plugs and see if there's any wet ones, but I'll bet dollars to donuts that I won't find any that are soaking wet.
Girlfriend is a 1990 with 10,900 miles, engine is as original. Plug wires were changed by PO, and I'll give him a call tomorrow to see if he ever updated the fuel injectors or had to mess with the coil packs.

I remember a post here in the last few months which sounded very similar to my experience. I'm just too lazy to go dig it out right now.
Advice, anyone?

TomC
'90ZR1 #792
Crabs is online now

tomtom72 · 08-21-2006

Tom,

Sounds a bit like my warning symptoms when my primary injector coils started to short out. One start cycle it was okay and then a slight miss and then a worse miss & worse & worse till it seemed like it was a 4 cylinder. Check for codes & if none then scan it & the fuel numbers will tell you something....if the coils short out usually it goes lean & sometimes if it's enough of the shorted coils you can smell the lean condition at the exhaust outlets.

Tom

tccrab · 08-21-2006

Tom:

Thanks for your input, I too am suspicious of the fuel injectors, especially after reading the thread from Greg Crowe in OK, and from what you describe. It was in the back of my mind from the get-go actually. I was hoping for the quick/cheap fix but it looks like a plenum pull and injector r/r.
*sigh*
I've not looked into how to measure the voltage/resistance on the injectors without pulling the plenum, anybody got directions and what numbers I should expect?

Thanks!

TomC
'90 ZR1 #792

tccrab · 08-22-2006

Pulled the plug wires one by one until the idle sound changed, well, in this case, until the idle sound DIDN'T change.

Cylinder #4 not firing.
Got plenty of spark, could hear that as clear as day.
Spark plug was dry and a whiteish color.
Couldn't hear the injector click using a poor mans stethoscope (long handled screwdriver).

Dug out the Helms, took a while to figure out the connectors and the naming convention, but the end results was:

Cyl-Ohms
1 - 13.9
2 - 16.3
3 - 15.6
4 - 4.5
5 - 16.4
6 - 16.3
7 - 16.3
8 - 16.4

Plenum pull here I come.

Anybody got any spare '90 primary fuel injectors lying around? I don't want to empty the savings account right now, me & wifey's anniversary is right around the corner and I'd be in big trouble if I blew a kilobuck on injectors right now.

TomC
'90ZR1 #792

guinnessdood · 08-25-2006

"Anybody got any spare '90 primary fuel injectors lying around? I don't want to empty the savings account right now, me & wifey's anniversary is right around the corner and I'd be in big trouble if I blew a kilobuck on injectors right now."

I am getting ready to buy the Accel 150121 injectors. They are available on eBay for $240 per 8 including shipping. You will need a set of O-rings from Marc Haibeck. Have a look at this on the Corvette Forum...

http://forums.corvetteforum.com/show...ighlight=accel

Uly

tccrab · 08-25-2006

Uly:

Thanks for the link to the info on the Accels.

I plan to yank my plenum this weekend and then I'll know what the condition of the secondaries are.
It's pretty clear that I'll need to repalce at least 3 of the primaries.

TomC
'90ZR1 #792

carmine · 07-18-2011

Where Can Buy RC Injectors

tomtom72 · 07-18-2011

http://www.rceng.com/ check'em out.

Tom

bdw18_123 · 07-18-2011

Tom,

You can also get 16 rebuilt Bosch II's for $350 from FIC. That's what I have in my '90 Z.

http://fuelinjectorconnection.com/sh...&productId=165

I do have all 16 of my original fuel injectors, but I don't know if they are any good anymore. I could ohm them out and send you the ones that ohm ok if there are any.

EDIT: Ok, never mind, didn't see how old this thread was. Do'h!! How about lets not ressurect old threads to ask a question? Just start a new one, sheesh...

XfireZ51 · 07-18-2011

Tom,

You may as well change them all while you're under there. It'll be cheaper than getting stuck somewhere. For the money do the FIC's, but I prefer the Accels. 3 years Flawless.

08-20-2006	#1
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,655	Sudden misfire after restart Took my oldest son out for a 20 mile or so ride in Girlfriend this afternoon. Started and ran fine just like always. Stopped by a buddy's house for 30 mins or so, then fired her up to go home. Started fine but as soon as I pulled out of the driveway it was obviously missing on at least 2 cylinders. At idle you can hear the dual mass flywheel rattle. Babied her home, seems to be ok at cruising speed, just low RPM's she's missing badly. On the way back home it seemed to run just a little hotter than usual, but never anywhere near the danger zone. After letting her cool off for about three beers I checked all the easy things, the hoses (map sensor hose first), spark plug wires, etc. No luck there, everything seems OK. Don't smell gas at the tailpipe so it's not mechanical. Tomorrow I'll dig out the Helms books, get my tools out, pull the plugs and see if there's any wet ones, but I'll bet dollars to donuts that I won't find any that are soaking wet. Girlfriend is a 1990 with 10,900 miles, engine is as original. Plug wires were changed by PO, and I'll give him a call tomorrow to see if he ever updated the fuel injectors or had to mess with the coil packs. I remember a post here in the last few months which sounded very similar to my experience. I'm just too lazy to go dig it out right now. Advice, anyone? TomC '90ZR1 #792 Crabs is online now __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

08-21-2006	#2
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Sudden misfire after restart Tom, Sounds a bit like my warning symptoms when my primary injector coils started to short out. One start cycle it was okay and then a slight miss and then a worse miss & worse & worse till it seemed like it was a 4 cylinder. Check for codes & if none then scan it & the fuel numbers will tell you something....if the coils short out usually it goes lean & sometimes if it's enough of the shorted coils you can smell the lean condition at the exhaust outlets. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

08-21-2006	#3
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,655	Re: Sudden misfire after restart Tom: Thanks for your input, I too am suspicious of the fuel injectors, especially after reading the thread from Greg Crowe in OK, and from what you describe. It was in the back of my mind from the get-go actually. I was hoping for the quick/cheap fix but it looks like a plenum pull and injector r/r. sigh I've not looked into how to measure the voltage/resistance on the injectors without pulling the plenum, anybody got directions and what numbers I should expect? Thanks! TomC '90 ZR1 #792 __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

08-25-2006	#5
guinnessdood Join Date: Oct 2004 Location: Woods Cross, UT Posts: 389	Re: Sudden misfire after restart "Anybody got any spare '90 primary fuel injectors lying around? I don't want to empty the savings account right now, me & wifey's anniversary is right around the corner and I'd be in big trouble if I blew a kilobuck on injectors right now." I am getting ready to buy the Accel 150121 injectors. They are available on eBay for $240 per 8 including shipping. You will need a set of O-rings from Marc Haibeck. Have a look at this on the Corvette Forum... http://forums.corvetteforum.com/show...ighlight=accel Uly __________________ Uly Past OWNER 90 ZR-1 #0120 Red/Saddle UT Plate: EZR1DER

08-25-2006	#6
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,655	Re: Sudden misfire after restart Uly: Thanks for the link to the info on the Accels. I plan to yank my plenum this weekend and then I'll know what the condition of the secondaries are. It's pretty clear that I'll need to repalce at least 3 of the primaries. TomC '90ZR1 #792 __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

08-22-2006	#4
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,655	Re: Sudden misfire after restart Pulled the plug wires one by one until the idle sound changed, well, in this case, until the idle sound DIDN'T change. Cylinder #4 not firing. Got plenty of spark, could hear that as clear as day. Spark plug was dry and a whiteish color. Couldn't hear the injector click using a poor mans stethoscope (long handled screwdriver). Dug out the Helms, took a while to figure out the connectors and the naming convention, but the end results was: Cyl-Ohms 1 - 13.9 2 - 16.3 3 - 15.6 4 - 4.5 5 - 16.4 6 - 16.3 7 - 16.3 8 - 16.4 Plenum pull here I come. Anybody got any spare '90 primary fuel injectors lying around? I don't want to empty the savings account right now, me & wifey's anniversary is right around the corner and I'd be in big trouble if I blew a kilobuck on injectors right now. TomC '90ZR1 #792 __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

07-18-2011	#7
carmine Join Date: Jun 2005 Location: Hanover,Ma. Posts: 179	Re: Sudden misfire after restart Where Can Buy RC Injectors

07-18-2011	#8
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Sudden misfire after restart http://www.rceng.com/ check'em out. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

07-18-2011	#9
bdw18_123 Join Date: Apr 2009 Location: Prather, CA Posts: 809	Re: Sudden misfire after restart Tom, You can also get 16 rebuilt Bosch II's for $350 from FIC. That's what I have in my '90 Z. http://fuelinjectorconnection.com/sh...&productId=165 I do have all 16 of my original fuel injectors, but I don't know if they are any good anymore. I could ohm them out and send you the ones that ohm ok if there are any. EDIT: Ok, never mind, didn't see how old this thread was. Do'h!! How about lets not ressurect old threads to ask a question? Just start a new one, sheesh... __________________ [IMG]http://i13.photobucket.com/albums/a292/bdw18_123/_zr1netforumsigphoto.jpg[/IMG][B] 1990 Corvette ZR-1 [/B][I] White/Flame Red, #2299, mostly stock, 144K miles.[/I] -Cams timed to the '93-'95 405HP LT5 stock timing. -IAT sensor relocated to below front bumper. -Haibeck hoops installed in airduct. -OBX cat-back exhaust. [COLOR=DarkRed][B](SOLD - December 2012 [/B][/COLOR][COLOR=DarkRed][B]:hello:)[/B][/COLOR] 1993 Corvette Coupe Black/Black, 6-speed (SOLD - October 2009 :hello:) Last edited by bdw18_123; 07-19-2011 at 12:54 AM.

07-18-2011	#10
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,708	Re: Sudden misfire after restart Tom, You may as well change them all while you're under there. It'll be cheaper than getting stuck somewhere. For the money do the FIC's, but I prefer the Accels. 3 years Flawless.