Hey guys so just got around to replacing my fuel injectors + O-rings (had 2 bad injectors), fuel filter, and fuel pressure regulator on my ‘99 LS.

Started up fine, got up to normal temp and it’s got a sporadic sputter. I can ease on the gas and it levels out and revs up nicely. I tap the pedal one good time and it sounds like maybe it’s starving for fuel. When she comes back down to idle it might stay at 800rpms for a couple seconds then it sputters down around 500rpms. Don’t see any leaking fuel or lines/connectors I may have not reconnected. Sooo.. fuel pump then?

Any advice would be much appreciated. Thanks

 

Also wanted to add I had DTC P0301 and P1399 which led me to the bad fuel injectors. So I had this issue prior to changing injectors, but it led me to finding the bad injector. The car sounds a little better than before but still getting codes. CEL flashes at low RPM, but goes solid above say 1500rpm. Haven’t driven the car only cranked it while parked.

 

Try using a scanner to clear the codes. Or try unplugging the ECU or battery terminal for a few mins and re connect to re set the ECU and clear the codes.

Okay, to test which cylinder or cylinders are misfiring, start the car up and let it idle. While the car's running, one by one, pull a plug wire out of a cylinder (remember not to ground yourself against anything).

If you pull a wire and the idle drops down a few hundred rpm, that cylinder is firing normally.

If you pull a wire and you don't hear the idle change, that cylinder is misfiring.

Also, if you have more than once cylinder misfiring, pulling one of the last remaining good cylinder's plug will probably kill the engine; it won't hurt anything, it's just kind of annoying to have to go back and start the engine lol.


Also, have you checked the resistance of the plug wires? I believe the rule of thumb is 10 kilo-ohms for each foot of the wire's length.



IMO Check the valve lash! its not very hard and the process is covered in most all manuals like Haynes etc. Or look on you tube on how to do it. I'm willing to bet you just need to adjust the valve lash if your ignition system is working fine as well as all the fuel injectors.

 

Thanks for the reply. Pulling the injector plugs is what led me to replacing the injectors. Number 1 plug didn’t change idle at all when I disconnected the plug from the injector. Now what I DIDN’T do, and I should have, was swap injectors to see if the injector was indeed bad or the plug/wiring for #1. I don’t believe it to be the plug as when I changed all the injectors it sounds better and will level out above 1500rpm but still has a constant miss at WOT. Which is why I’m suspecting fuel issue, but could certainly also be valve related, she’s not smoking so I think rings are ok. Spark plug wires were replaced 2 years ago, but I’ll check the resistances, I have a multimeter. Spark plugs looked alright. Just trying to get some advice before opening the motor up.

Gonna run compression and fuel pressure check probably over the weekend and see what I get. Car has a lot of miles so wouldn’t be surprised by anything, just haven’t ever come across an issue quite like this one.

Distributor was replaced last year, igniter failed on the old one. Cannot remember for the life of me if it was a reman though, but I’m almost certain I bough brand new and not refurb.

I’ve got a Haynes for it, never done valve adjustment before but I’m confident I can do it if necessary. Any suggestions on feeler gauges?

 

Perform the valve lash adjustment, if it has allot of miles chances are they need adjusting! do it when the engine is stone cold, any feller gauge will work, i like to put a little Lucas engine assembly lube on the feeler gauge this helps you feel the drag. After you tighten the valve nut re check the lash as sometimes soon as you tighten the nut you can make the valve tighter so always check it again after. It takes some practice but take your time, use the correct valve tool looks like a screw driver with a socket attached with a handle.

 

cheapest deal on ebay, these things are getting expensive:

https://www.ebay.com/itm/29371086564...75.c101224.m-1

 

Much appreciated guys I’ll pick up a set of gauges over the weekend and get a valve tool on order. Thanks for the link to the tool on eBay, now I know exactly what I need to get. I’ll post an update back here soon. Thanks a ton for the help so far 👍🏻

 

That's the one i have!

 

**FIXED**

Checked resistance on plug wires and manual says less than 25k ohms, all within spec and number 1 wire was 13.25k ohms. Checked plugs all looked normal except 4 looked lean. But went ahead and replaced wires anyway bc I couldn’t remember if I replaced them when I got the car 4 years ago so wasn’t sure how old they were. Then put in new ruthenium spark plugs, and some fresh gas in it and haven’t had the issue since.

Hate the thought that I skipped a simple step to avoid buying a bunch of new stuff that wasn’t necessary (injectors, regulator, etc). Had I just swapped a few injectors around I would’ve known immediately it wasn’t a fuel related issue. But then again sometimes trial and error is as good a way to learn as any.

Will likely still do valve adjustment and run a compression test just for ***** and giggles, bc at 263k miles I’m sure it’s long past due for it.

thanks for all the advice guys. Much appreciated 👍🏻