Check Engine Lite

sorren · 07-29-2005, 05:38 AM

Got a Check Engine Lite on 98 323 Conv with about 30K miles. Peake reader said Fuel Injector Cyl 1. Cleared the Check Engine Lite, but it returned after about 45 min. of stop/go drive. Car runs with no apparent problems. Is there a simple solution, or is this a real problem?

blkongry · 07-29-2005, 06:47 AM

This just means some sensor is getting skewed enough to trip the computer. It sounds like it's not a major problem, but it may eventually become a nusance. You may want to pull the injector and just take a look at it. I've had the 'check engine' light come on in my 4Runner before... stays on a couple days, then pops back off. Sometimes it's just condensation, bad gas, or some other minor anomoly.

If I were you, I'd drive it for a bit, see what happens, and if it stays on or you get a hint of it running strange, then pull the injector and take a look. Either way, make sure you keep an eye on everything.

sorren · 07-29-2005, 07:13 AM

Thanks for the reply. What do you think about using a fuel injctor cleaner likr Techron?

blkongry · 07-29-2005, 07:28 AM

I use Techron regularly (I get the 4-pack at Costco). It's a good preventative measure, and that might just clear up what's tripping the ECU.

Jeron · Jeron's Garage

I almost bought some Techron cleaner the other day. When I was looking, I noticed that they (Pep-boys) had two different types one had Techron and the other looked almost the same but didnt say Techron on the bottle. Be careful.

How much is a 4-pack at Cost-co?

blkongry · 07-29-2005, 08:15 AM

Yeah, I was pouring in the Techron at the gas station the other day and the attendant was waiting to fill my ride (you can't pump your own gas here in Oregon... dumb law), and the guy asked me what stuff I was using. I showed him the Chevron bottle and he said, "Oh, that's good stuff, but there is another Chevron version that has..." and I can't remember what he said was in it. I'm thinking, "It's cleaner, and a once-through the tank... it's probably not that much difference", but I would stick with the Techron since I think it has some Teflon in it and helps lubricate (of course, who really knows what they put in it).

Anyhow, if I remember right, the 4-pack was $6 (don't quote me on that, though... I bought it a while ago, but I remember it was a much better deal that buying a lone bottle).

Jeron · Jeron's Garage

Wow. Techron is $6-8 for a single bottle at Wal-mart and Pep-boys, IIRC.

blkongry · 07-29-2005, 08:50 AM

Just to make sure we are talking about the same stuff, here's the link. It's Chevron's Pro-Gard with Techron (the one in the blue label bottle... uh, wait, you said you were colorblind, huh? ...then it's the second bottle down on the page). http://www.chevron.ca/ProductsServices/Retail/EngineAdditives.htm

Jeron · Jeron's Garage

That explains it.

It the top one, the Techron Concentrate that I'm referring to. I don't think the Pro-Gard has Techron. It seems they are trying to use the brand awareness and common referrals of Techron to cross sell the Pro-Gard product line. Nice that the bottles are so similar.

My original point is that I would only buy the Techron product because I see it recommended very often. Also, you have to be careful of lookalikes.

944_S_type · 07-29-2005, 12:31 PM

I am an aircraft mechanic, When we get strange faults as you are describing. we sometimes move componets around to see if the problem follows. Mabyee you should try to switch injectors number 1 and 2. Then clear the check engine light. If the Light comes back and it faults Cylinder #2 then you have confirmed that the injector is in fact at fault. If it faults number one again, Further troubleshooting will be required.

blkongry · 07-29-2005, 12:33 PM

Ah, okay, that makes sense. Yeah, the Pro-Gard fuel injection cleaner says, "With Techron technology," but who knows if that means there is actually Techron in there or not. Either way, Chevron lists their products by the symptoms (probably relates to how aggressive of a cleaner the stuff is), and I think the Techron is one of the more aggressive and effective cleaners, but one might not need it. Sorren, I'd say go for the Techron, or Fuel Injector Plus... if it doesn't clean up your problem, then it may be a seal issue.

Wayne 962 · Wayne 962's Garage

Hmm, the car has no real way of telling how an individual cylinder is operating. The knock sensors measure banks (1-3 and 4-6), and the O2 sensor(s) measure cumulative output from the exhaust. Even if there was a completely clogged fuel injector, I'm not sure how the car would be able to measure or figure out what the flow is.

That said, the error signal indicates some type of electrical fault. Whether or not the fault may be caused by a clog - I'm not intimately familiar with the injectors to know what feedback they give to the computer. I know that they have only two wires running to them, so the result back to the computer must be measured resistance. So, the computer is telling you that the resistance from the injector is not the proper value. This could mean that the internal coils inside the injector are failing from years of use. Or, if there is a clog in the injector, it may be "pushing back" on the electrical current. If you have a ceiling fan that is running versus one that is stopped by you holding it in place (while electricity is running through it), a controller powering the fan will be able to tell through resistance and the appearance of what is known as "back EMF".

944_S_Type has it right with troubleshooting a circuit or wiring fault in the wire harness. If the injector is bad, then moving it will make the fault follow it around. If the problem is in the DME, fuel rail, or wire harness (less likely), then the problem will stay with that cylinder.

Bottomline, I would just replace the injector. Here's a tech article on the subject:

http://www.pelicanparts.com/bmw/techarticles/E36-Injector-Replacement/E36-Injector-Replacement.htm

and here's a link to the fuel injector section in our catalog:

http://www.pelicanparts.com/BMW/catalog/shopcart/BE36/POR_BE36_fuelij_pg2.htm#item15

-Wayne

blkongry · 07-29-2005, 01:25 PM

Yeah, I don't know how one would check for the electrical performance of an injector, since they are essentially a solendoid, and the vehicle power generates a magnetic field that simply moves the plunger in one stroke... it's not like a continuous rotating motor with a generated back EMF that you can measure. Plus they are just a valve, and the valve may be opening properly, but the pathway is clogged. I don't know where the ECU is picking an injector fault from, but I would try some cleaner before pulling anything apart and replacing pieces. If you do have to, then Wayne's article will walk you through it nicely.