Bad gas mileage just got worse

[Ecomike]

No problem, at least you can ask an understandable question, LOL! Some of the gibberish we see posted takes a decoder ring, LOL!:doh:

Ohms does not care about positive or negative. Disconnect the wiring from the injector, and for starters try using the 2K range, which will display 0-2000 ohms, or an error if over 2000 ohms. Then touch each of the two probes to a separate pin on the injector. The meter sends a battery voltage through the injector and measures the resistance (by measuring the voltage drop, using Ohms law).

I suspect the readings will be under 200 ohms, probably around 15 to 20 ohms each, but I could off on that, they could be closer to 100 ohms for all know. If you get readings under 200 ohms, you switch to the 200 ohm scale then to get better precision in the readings. But for this kind of work, we usually look for shorts at 0-2 ohms, or over a 1,000,000 ohms for a dead connection, open wire, or a GOOD coil, like the transmission solenoids that are about 14 ohms.

 

[SBpunk]

Ok be right back with the results

 

[SBpunk]

Ok reading 0.017 on all the injectors

 

[Ecomike]

Ok reading 0.017 on all the injectors

That can't be right. Is the meter battery good? Do you have the probes in the common (black -) and Ohms (Omega symbol, +red) connections on the meter side of the probes? Sounds like you have a probe in the volts side instead of the omega-ohms hole?

Is the selector set for ohms?

There are so many different meters now, that have their own little quirks-settings, you may need to check the manual on the meter? Drives me crazy when I go from one to another style (I have several), .....I forget to move the probes on one.

 

[SBpunk]

'

see if that works

 

[Ecomike]

Hmm, kinda hard to make a mistake with that one, try the 200 ohm scale, if it reads the same, then check to see if a fuse is blown inside the meter.

 

[SBpunk]

Fuse is good and im getting a 15.8 reading

 

[Ecomike]

OK, my mistake, I hate these new digital meters (some of them anyway, they have some screw ways of displaying data), I just checked one I had handy, and I got the same garbage, but on the 200 ohm scale I got 16.6 ohms on a good injector.

On the 2K scale it reads .016, which makes no bloody sense to me at all, and never has. I like my 40 year old analog meter!!!!

 

[SBpunk]

Lol no worries. Its reading between 16.2 and 15.8 on all of them. Guessing the injectors are good. Think the PCM is fried? Would it be causing only 2 injectors all the sudden throwing codes? Don't get me wrong, we were pulling the connectors off to see the engine reaction while it was running... Like I said I'm horrible at electrical work. I can match wires but thats about the extent of my talent.

 

[Ecomike]

So, it sounds like you have 6 good injectors!!!

Unfortunately that means either a bad criscrossed wire or two in the injector harness, god knows where, or a bad PCM/ECU.

I would exhaust looking for a damaged, burned, cut, crushed wire and check the #1 and #6 wires before I assumed it is the computer, as a shorted wire may have damaged the computer, and if so would damage a replacement computer!!!

Just for fun, check the prior injectors, see if any were bad, shorted internally.

 

[SBpunk]

Crap I was hoping it wasnt the PCM. I'll explore the wires and see if I can find any screwed up ones. I don't want to order a new PCM (remanufactured) and hook it into bad wires. The NOID light would still be blinking if there is a short somewhere?

 

[Ecomike]

Lol no worries. Its reading between 16.2 and 15.8 on all of them. Guessing the injectors are good. Think the PCM is fried? Would it be causing only 2 injectors all the sudden throwing codes? Don't get me wrong, we were pulling the connectors off to see the engine reaction while it was running... Like I said I'm horrible at electrical work. I can match wires but thats about the extent of my talent.

If you pulled the connections while the engine was running that would have set the codes!!!! And once those codes are set the computer will not fire those injectors until the computer is reset!!!!! Unless you have a scanner, the way to reset is to disconnect the battery for a while, but then you need to drive it a while until the computer relearns all the sensors and locks in all the parameters, During that time it will not reset some codes, so beware, it is easy to get a false sense of things being fixed, when they are not.

 

[SBpunk]

I have a scanner and deleted the codes. Before that I reset the battery and drove it around a bit. All the other codes cleared and stayed gone (had codes on all 6 which I expected) but 301 and 306 keep coming back. The injectors im using are http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&vxp=mtr&item=190805125969... sorry about the link but I cannot remember the bosch number. Once I put them in the engine went to shit and thats what made me start digging in the first place

 

[Ecomike]

Crap I was hoping it wasnt the PCM. I'll explore the wires and see if I can find any screwed up ones. I don't want to order a new PCM (remanufactured) and hook it into bad wires. The NOID light would still be blinking if there is a short somewhere?

The Noid light might not see a weak ground or low voltage, or a crossed wire, it would see a cut open wire (light does not flash), or the total loss of the ground or power (light does not flash). Keep in mind a bad wire may be damaged insulation that only grounds out when the wire moves because the engine moved!!! So the Noid light might say it is OK until you wiggle the hell out the wires, just the right way, when the moon is full, on Thrusdays, LOL. Those are what we call Stealth Morphidite Electrical Jeep Gremlins, SMEJGs, the nasty ones!!!!!Hasta

 

[Ecomike]

I have a scanner and deleted the codes. Before that I reset the battery and drove it around a bit. All the other codes cleared and stayed gone (had codes on all 6 which I expected) but 301 and 306 keep coming back. The injectors im using are http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&vxp=mtr&item=190805125969... sorry about the link but I cannot remember the bosch number. Once I put them in the engine went to shit and thats what made me start digging in the first place

So after clearing the codes with the scanner, to 201 and 206 codes came back? In that case I would check the wires now on #1 and #6

 

[SBpunk]

No all of them gave me the same reading. Even the injectors I bought from Precision Injectors turned out to be good (definitely owe them an apology) lol

 

[Ecomike]

Testing the wires on #1. Disconnect the PCM and the #1 injector. Then at the injector harness connection test between the two female injector connectors using the ohm scale. It should read over a megohm, 1,000,000 ohms. 500,000 ohms or less is suspect!!!!!

Then you may need a very long test wire so you can test each wire end to end for continuity (or is your PCM under the hood? Mine is under the dash, 87-89 jeeps). Each wire should read less than 1 ohm, should read as a dead short. Redo the tests while someone wiggles the hell out of the harness wires!!!

Then repeat for #6.

 

[Ecomike]

Also check and make sure the computer pins and female contacts are clean and tight, and that none have gotten bent!!!

I have one bad female injector connection on mine that is a sometimes contact I need to replace. I can wiggle the connector up or down on that one injector and make the engine miss or purr!!! Mine are pre OBD-II, but yours might detect that kind of sloppy contact.

 

[SBpunk]

AH HA! just pulled the plastic cover off the wires going just behind the fuel rail and the motor picked up just a little. Cleared the codes and P0206 is gone. So I started messing with the wires going to the connector. Definitely the bad spot on number 6. So I'll be looking for new connectors. Ill test out the #1 in the morning. Hopefully this will get me to work in a few hours.

Just to be clear disconnect BOTH grey and white PCM connections then run the test wires from the piece that clips into the fuel injector and the other side on the PCM connector side?

 

[Ecomike]

AH HA! just pulled the plastic cover off the wires going just behind the fuel rail and the motor picked up just a little. Cleared the codes and P0206 is gone. So I started messing with the wires going to the connector. Definitely the bad spot on number 6. So I'll be looking for new connectors. Ill test out the #1 in the morning. Hopefully this will get me to work in a few hours.

Just to be clear disconnect BOTH grey and white PCM connections then run the test wires from the piece that clips into the fuel injector and the other side on the PCM connector side?

Nice! Glad I mentioned that. Took me 6 years to find it on mine, LOL! It was a slight, occasional miss at idle on mine.

And yes that is right. I assume you have the FSM and wire colors to follow, as to which wire is which at the computer side?

WE should probably make the wiggle test a sticky note around here, LOL.

I found new injector connectors on Ebay pretty cheap.