1999 T5 v70M56 Elizabeth erratic miss [ bad spark plug] Topic is solved

Post by **abscate** » 08 Apr 2022, 04:22

Gave the T5 her first 100 mile run since the big valve job. All went well. Got the timing belt in and got rid of the cam code error

On float and at idle I have an erratic miss. Perhaps every 5-15 seconds, irregular, she skips a beat.

It could be happening at high revs and ZO just don’t notice. No misfire codes present or pending. I don’t think ME7 supports misfire count but will investigate.

Quick check if fuel Pressure shows52 psi solid

Troubleshooting plan

Will cycle new plug and coil through cylinders and test drive. Might be able to hear skip at idle

Possible sticking fuel injector

Possible sticking valve.

Post by **scot850** » 08 Apr 2022, 09:43

On the last one, you could do a compression test and may highlight or hopefully dismiss that as an issue!

I think your other suggestions are more likely, in particular a possibly failing coil pack.

Did you replace the injector seals when you did the head?

Neil.

Post by **BlackBart** » 08 Apr 2022, 10:09

abscate wrote: 08 Apr 2022, 04:22 Will cycle new plug and coil through cylinders and test drive. Might be able to hear skip at idle

This sounds smart - eliminate basics.

Post by **abscate** » 08 Apr 2022, 11:48

I did not replace injector seals but I removed the fuel rail as a unit. I think trims would go out if range if I had a vacuum leak

Post by **misha** » 08 Apr 2022, 14:49

My bet is that fuel injectors are a bit clogged from sitting too long without fuel.

Fuel residue dryed out and clogged the inlet or outlet at least on one injector or all of them at some point.
Nothing major but enough to feel a miss.

Clean them all before you proceed further.

Post by **abscate** » 08 Apr 2022, 19:00

Misha…should I use a tank product or pull them and send them for cleaning ?

Post by **rguzz** » 08 Apr 2022, 21:42

If you send them out I've had great luck with Mr. Injector. Somewhere in the mid west IIRC?

Post by **misha** » 09 Apr 2022, 02:19

abscate wrote: 08 Apr 2022, 19:00 Misha…should I use a tank product or pull them and send them for cleaning ?

I would send them to a professional.

That way you will have insight in their condition before and after cleaning and i would start from there.

I once bought injectors for my XM which came from a parts car that ran great,but they were removed from a car along with fuel rail for not more than a year.
When i installed them in my XM the car was missing pretty bad.Injectors are Bosch.

All back to normal after cleaning.

Post by **abscate** » 10 Apr 2022, 05:14

Life work imbalance getting me this week, won’t get back into this until after Easter. I will try some Lucas in the tank to see if that helps clean the injectors

My gut is telling me it’s a bad coil/plug combo.

Post by **abscate** » 11 Apr 2022, 07:10

Took the car to airport for a 0600 flight. About 12 mile trip. Ran great. Still have that skip at idle and float. Will play whack-a-coil after Easter.....