miss after car warms up - ZR-1 Net Registry Forums

aafc · 03-24-2015

Hi,
I have a miss condition when driving the ZR-1 after about 25 miles, then
the miss starts. The engine temp is between 185 deg. to 191 deg. The miss
is a gurgling sound at low speed or when more throttle is applied.
The tech 1a shows no codes , all readings look ok per FSM for 1990 car.
I have rpl the coils , rpl fuel filter ( some water in filter) drained the tank
about 5.5 gals. refill with fresh gas and seafoam for 10 gals. Drove car
but same trouble after car reaches operational temp.
Waiting for compression gauge to do that test. Org. wires rpl at about
66000 miles. car has 127400 miles.
What else can or should i do to resolve this condition?

THANKS
John Becker
1990 white/black #2546
one of a few auto (4l80E) eq. ZR-1's

batchman · 03-24-2015

Have you changed injectors yet? I just have a feeling...

Best,
- Jeff

Franke · 03-24-2015

Quote:

Originally Posted by batchman

Have you changed injectors yet? I just have a feeling...

Best,
- Jeff

I tend to agree with Jeff.
Measure the resistance of the injectors when hot. I had 4 bad ones but only when hot. When cold they measured ok. They were the original injectors and failed at 55K miles. If yours have been changed its still a possibility one could be bad electrically or mechanically. Good luck.

aafc · 03-24-2015

Injectors rpl in May 2012 with FIC @ 117141 miles. I have not checked
the readings of the injectors , will try that after comp check. Also i'll
check inj leak test before resistance check. Warm motor to 179 deg. then wait
10 min ,due comp check. then leak test and then resistance check.
Thanks
John Becker

Karl · 03-24-2015

Check the oxygen sensors. I replaced mine and the difference was night and day. The sensors looked original and will not necessarily throw a code if bad.

Paul Workman · 03-25-2015

Dittos on the injectors, AND what Karl said as well. Both of these items (at different times) caused a miss for me w/o throwing any codes.

One more item might be to ohm out the coils; another one of those items that often show up only after they are up to operating temperature.

aafc · 04-05-2015

Update:
Have been working for the last 3 days so no time to work on car. Order
new gaskets from Jerry (used my last spare set). also picked up new plug
wires . Well plug wires came in Wed. morning and after installing them
mail shows up with my gaskets (thanks Jerry). While car was apart i did
the TB bypass. After putting it all back together made my test run 55 miles
local and highway , no more miss at low or high speed.
So what i replaced is
Coils ( first set was bad they took them back and got the best set of coils).
o2 sensors they were black from miss fire.
Plug wires ( this i'am sure was the main root of my miss ).
injectors check out ok
did not do comp check

Thanks to all who help steer me in the right direction.

John
1990 white/black #2546
one of a few (4l80E ) eq. Zr-1's

Blue Flame Restorations · 04-05-2015

Happy to hear of your success!!!

Billy Mild · 04-06-2015

I have been having a slight bucking under 2,000 RPM occasionally. It seems after the car is warmed up. I just replaced all my coil packs a week or so ago. It still bucks a bit.

I replaced my injectors with Accell injectors, spark plug wires with Denso OEM ones, and single platinum autolite plugs.

I'm starting to think my ECU has some issues. My service ride control is on, and occasionally my Service ABS light comes on.

BigJohn · 04-06-2015

Could it be the Autolites?

03-24-2015	#1
aafc Join Date: Feb 2010 Location: Summerfield, FL Posts: 433	miss after car warms up Hi, I have a miss condition when driving the ZR-1 after about 25 miles, then the miss starts. The engine temp is between 185 deg. to 191 deg. The miss is a gurgling sound at low speed or when more throttle is applied. The tech 1a shows no codes , all readings look ok per FSM for 1990 car. I have rpl the coils , rpl fuel filter ( some water in filter) drained the tank about 5.5 gals. refill with fresh gas and seafoam for 10 gals. Drove car but same trouble after car reaches operational temp. Waiting for compression gauge to do that test. Org. wires rpl at about 66000 miles. car has 127400 miles. What else can or should i do to resolve this condition? THANKS John Becker 1990 white/black #2546 one of a few auto (4l80E) eq. ZR-1's

03-24-2015	#4
aafc Join Date: Feb 2010 Location: Summerfield, FL Posts: 433	Re: miss after car warms up Injectors rpl in May 2012 with FIC @ 117141 miles. I have not checked the readings of the injectors , will try that after comp check. Also i'll check inj leak test before resistance check. Warm motor to 179 deg. then wait 10 min ,due comp check. then leak test and then resistance check. Thanks John Becker

03-24-2015	#5
Karl Join Date: May 2013 Location: Chicago Posts: 982	Re: miss after car warms up Check the oxygen sensors. I replaced mine and the difference was night and day. The sensors looked original and will not necessarily throw a code if bad. Last edited by Karl; 03-24-2015 at 05:45 PM.

03-25-2015	#6
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: miss after car warms up Dittos on the injectors, AND what Karl said as well. Both of these items (at different times) caused a miss for me w/o throwing any codes. One more item might be to ohm out the coils; another one of those items that often show up only after they are up to operating temperature.

04-05-2015	#7
aafc Join Date: Feb 2010 Location: Summerfield, FL Posts: 433	Re: miss after car warms up Update: Have been working for the last 3 days so no time to work on car. Order new gaskets from Jerry (used my last spare set). also picked up new plug wires . Well plug wires came in Wed. morning and after installing them mail shows up with my gaskets (thanks Jerry). While car was apart i did the TB bypass. After putting it all back together made my test run 55 miles local and highway , no more miss at low or high speed. So what i replaced is Coils ( first set was bad they took them back and got the best set of coils). o2 sensors they were black from miss fire. Plug wires ( this i'am sure was the main root of my miss ). injectors check out ok did not do comp check Thanks to all who help steer me in the right direction. John 1990 white/black #2546 one of a few (4l80E ) eq. Zr-1's

03-24-2015	#2
batchman Join Date: Jun 2009 Location: I live at Devens, one run at a time Posts: 454	Re: miss after car warms up Have you changed injectors yet? I just have a feeling... Best, - Jeff

04-05-2015	#8
Blue Flame Restorations Join Date: Feb 2010 Location: Pendleton, IN Posts: 3,899	Re: miss after car warms up Happy to hear of your success!!! __________________ 1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project

04-06-2015	#9
Billy Mild Join Date: Aug 2014 Location: Kansas City, MO Posts: 835	Re: miss after car warms up I have been having a slight bucking under 2,000 RPM occasionally. It seems after the car is warmed up. I just replaced all my coil packs a week or so ago. It still bucks a bit. I replaced my injectors with Accell injectors, spark plug wires with Denso OEM ones, and single platinum autolite plugs. I'm starting to think my ECU has some issues. My service ride control is on, and occasionally my Service ABS light comes on.

04-06-2015	#10
BigJohn Join Date: Feb 2012 Location: Ledyard,CT Posts: 8,330	Re: miss after car warms up Could it be the Autolites?