Well, I verified about the injectors, they even look different. The front 4 are skinny and the rear 4 are fatter looking.

All mine are reading 15 ohms. Its leading me to believe its not closing all the way and my mom has a leaky injector on her hands.

 

Does impedance change according to open or close? All of mine are reading ~ 15-16 ohms also. My new #8 spark plug is not carboned up and black looking... rather dark brown and wet, unlike the other 7 plugs which are very light brown and dry. So what does mean the injector is doing? Does it have a bad spray pattern and not atomizing correctly? Is it intermittently squirting fuel? Is it squirting at all? How would I know if it's leaking like in your mom's car?

I can't substitute my spare 240cc DSM injector in there because the plug is different. I'm just going to move the suspected bad injector to another location and see if the problem follows it.

 

I'm only a backyard mechanic The questions youre asking are beyond my mechanical knowledge.

My mom is dropping off the car at her local shop on Monday, they work on foreign mostly and the owner is an ex-Lexus mechanic so hopefully theyll figure it out.

Pulling off the fuel rail and swapping out the injector is more than I can handle at this time, I have a couple herniated discs in my lower back and I cant be hunched over the hood for extended periods. Even doing what I did made me pretty sore.

I'll keep you informed about their diagnosis.

Good Luck

 

One other trick I know to find out if the injector is at least opening and closing.

With the car running, take a long screwdriver and hold it up against the injector. You can actually feel it pulsating or vibrating as it opens and closes. If you put your ear up to the end of the screwdriver you can also hear it.

 

PROGRESS REPORT:
Pete,
I was out working on the car when you last replied. I ended up pulling the fuel rail for injectors 2-4-6-8. The front two injectors ARE different in appearance, BUT they are actually the IDENTICAL part. The "fatter" looking rear injectors are the same, the fat part you see is just a soft, black, foam sleeve that is on there. The foam must be for some type of heat insulation or something. If you pull the foam back you'll see that all the numbers imprinted on the injector are the same as the fronts.

I visually inspected the bad injector and of coarse it looked normal. I wanted to see if I could get the solenoid in the injector to open and close. Due to lack of proper tools I just used a standard 9v battery and some test leads and tried to pulse the injector. It did not open nor make any clicking sounds. The other 3 injectors I had out opened and clicked like they should. Now I KNOW that my #8 injector is bad. It's stuck in the closed position yet still measure the same impedance (~14-15ohms) as all the other injectors.

I'm going to try and clean it and possibly free up the internal mechanism. Here's what I did so far tonight: attached a 18" small rubber vacuum hose to the injector inlet and poured some Seafoam into the tube. Connect the other end of the hose to a air nozzle from my air compressor set to about 50psi. connected the 9v battery to the injector to try and open it. While the 9v battery was connected I put about 50psi of air into the vac hose in order to push the Seafoam through the injector. It didn't work! The injector pintle is stuck. I'm going to soak the bottom half of the injector in Seafoam and hopefully it might loosen up the gunk that it keeping it closed.


BTW, Does anyone have a spare injector they'll sell to me??

 

Here's a pic, specs, and Denso part number of stock injectors in our GS400's

 

Thats some good work and info!! But I was inspecting the injectors and I did not notice any foam sleeve, the injector itself was fatter. I was even tapping it with a screwdriver hoping to loosen whatever is making the injector stick. But I could be wrong.

One thing I do know is when mechanics use high pressure to blow out stuff from the injectors they use like 120psi. The 50psi you used was not enough because you basically just mimicked what the injector is already seeing. I'm not sure what the regular fuel pressure is in a GS, but in my Z06 its upwards of 50psi, especially with my blower.

I'm glad you found the culprit, it must be a good feeling.

 

rysbrnr, you are very resourceful. And congrats.

If time allows, I would send off all the injectors to get cleaned and balanced.
Here is a link to the service I have used http://www.cruzinperformance.com/fuelinj.html

 

I hope you didn't damage your injectors by putting 9 volts on them. The computer runs 5 volts Dc across all the injectors at the same tme, and then pulses a "negative" or "ground" to one side of the injector coil when it wants that injector energized causing fuel flow. That cylinder then electrically fires with spark from the ignition coil and spark plug at just the right time for the explosion.

It seems that the coil part of the injector was good. It seems to have been a mechanical issue with the stuck pintle not releasing fuel into the combustion chamber.

What type of fuel do you use? Have you used any injector cleaner in the fuel system lately? I am assumng that your car is a "daily driver" like mine, so the stuck injector is not a result of lack of use. I use cleaner somewhat regularly. Most good fuels already have some cleaner in them, but since I don't know for sure which do or don't, I add my own cleaner. I now have 168,000 mles, and no problems with injectors yet.

Since you have the rack out, I would suggest having all the injectors cleaned. Replace all tthe black rubber o-rings as well, or a fuel leak could result.

Also change the copper gaskets under and above the regulators on the end of the racks if you change the o-rings. The regulators have to be removed to get to the o rings. They screw into the rack and have to be torqued down.

With all good injectors, your car should be running strong when you are done. GOOD LUCK.

GSEREP1

 

The air pressure should be supplied from the pintle side. By design, fuel pressure helps keep the injector closed. So pressuring the supply side of an injector actually won't help to clean it out.

 

The reason I only used 50psi on the inlet side was to simulate running fuel pressure. I had a lil bit of seafoam in the rubber hose and was trying to push it through the injector while pulsing it on/off with my 9v battery. I bumped the air pressure to 120psi and tried forcing air in to the pintle end with the plastic pintle (gray piece) cap removed. The fuel did squirt out the inlet end despite not being able to open it electrically so I'm sure there's some kind of mechanical malfunction in there. I would send this off to a fuel injector specialty shop but tomorrow I'm just gonna drop it off at a local injector shop to see if there's any hope for it. If it's bad I'll buy another used one and send all 8 off to a injector performance service shop.

Gserep, A couple times a year I usually run a Chevron Techron in-tank injector cleaner on all the cars as preventative maintenance. I run premium in this car but someone borrowed it a couple weeks and was "thoughtful" enough to refill it with that ethanol crap. It probably loosened up gunk and sent it through the fuel system where it ended up in my injectors. I don't think I damaged the injectors with that old 9v battery. It actually measured more like 7v at the time. I didn't have access to adjustable power supply at 11pm saturday night so I used an old 9v battery. It's a low enough current that it won't cause any damage to the coil windings with the short pulses I did.

FrankT, thanks for the compliment. The reason I am somewhat resourceful is because I've been a long time owner of a DSM (Talon/Eclipse turbo AWD) since 1994. I've had like 8 of them and modded/raced them for years. It's mostly because I'm DSM gearhead and my job as avionics electronics technician which helps out a bit when it comes to troubleshooting theory. Plus I hate getting raped by dealerships and their so-called service techs. All too often they give incorrect diagnostics making the customer pay $$ for "guess" because their terrible "shotgun" troubleshooting was wrong. Very few of them are truly good and most of them are just parts replacer rather than skilled mechanics. Many good mechanics run/work in independent shops working on many different type of vehicles keeping their minds fresh with new problems day-to-day.

 

GREAT! You certainly sound like you know your business, and it is evident that you take good care of your vehicles. Being "raped" by the dealers is painful experience I wouldn't enjoy either. I just changed my passenger side engine mount after being quoted $266.00 for labor by Lexus. I did it myself, thank you.

I wish you only the best, and I can stand to learn a few things from others. The "weak" 9V battery and quick pulses probably did not do any damage. I see wannabe mechanics hok up full 12V battery power to theirinjectors and them wonder why they are burned out.

I too am not a fan of that ethanol stuff. You are right....something dislodged some material, and it sounds like it ended up in your injectors. I try to stay with name brand fuels, but when driving across the country like I do each summer, I am not sure just what I am getting. I really put a lot of either TECHROLINE from Chevron, or Performance Improver (P.I. from AMSOIL). Other than my wife occasionally, I am the only driver of my car.

So far so good! Please keep in touch, as I am looking to hear of a successful solution to your problem. I check everyday, ha ha!

 

I've probably saved THOUSANDS of dollars doing my own maintenance for the last 15 years...damn thats a good feeling...

 

I was going through some old service records from the local Lexus dealer that the previous owner gave for my GS4. She paid $58 to install ONE low-beam and ONE high beam bulb.

A few months later she had a bill for $1,192 for new brake pads on front/rear, caliper servicing (lube the slider pins) and resurfacing 4 rotors.... and that's with the a $120 customer appreciation coupon!!!

I'd appreciate the customer too if I was allowed legal robbery!

I should frame that receipt to remind of the money I'm saving next I'm pissed off about doing minor work to my car.

 

My moms car ended up just having a bad #5 injector, all fixed and running 100% again.