ZR-1 Net Registry Forums - missing under load under 2k

ZR-1 Net Registry Forums (http://zr1.net/forum/index.php)

- C4 ZR-1 Technical Postings (http://zr1.net/forum/forumdisplay.php?f=9)

- - missing under load under 2k (http://zr1.net/forum/showthread.php?t=15196)

Re: missing under load under 2k

Quote:

Originally Posted by mlotruglio (Post 119292)

I have never had much luck with testing by pulling off the wires but now that you gave a color and size Im going to try it I will get back to you !!!

Thanks!!!!=D>

Pull all plugs look to see which has a different color, if its black it could be leaking inj if its white it is too lean on that cyl again inj problem.

Tyler

Re: missing under load under 2k

Quote:

Originally Posted by mlotruglio (Post 119289)

My shop manual and parts book say that is the altitude sensor. Im going to have to look deeper in that. I have no lights, and it never really goes away Full power and Normal Power both miss, I have not heard it at idle ( cant feel it) Dont think so though Hot cold same The exhuast smells right. As far as a scan tool I have a obd 2 but That dose not help me.
Its really stumping me:mad::confused:

I would try looking at the plugs to see if they have anything to tell you. Also, refrain from removing a plug wire one at a time while the motor is running as the DIS box doesn't like that too much and you could damage it eventually.

On the scan tool, if you have a rather good one most offer an adapter. This adapter is a two sided connector that plugs into the OBDII connector already on the machine and it has an ODBI pattern so it can plug into an OBDI ALDL socket in the car. The only rub is you need the software for your yr Z and then you can run diagnostics. Do you by chance have a snap-on MT-2500? If yes I could lend you my software ( I'll have to check if it goes to 91 ) and my OBDII to OBDI adapter plug.

Okay, I should read more carefully!:o Since the miss is constant in either full or normal, and you have no SES light ( even briefly like it's winking at you ) and you changed the coils & wires & plugs and the exhaust doesn't smell lean or rich.....the work that was done was done after it sat for two yrs: plugs, wires & coils? You didn't notice any evidence of mice chewing any of the under plenum wiring? Did you notice any chaffing of the injector harness at the injectors ( one of our brothers found a chafed injector wire that got pinched when he put the plenum back on ) or any carbon tracking on the coil mounting block or anything out of the ordinary under there? You got that vacuum line plugged in at the lower right side of the throttle body? I'm just thinking out loud here, sorry.:o

Look at the plugs first as Tyler said and then do the spark quality test as Jerry said.

Re: missing under load under 2k

Yes I bought her after her long "nap". My scan tool is a $300 advance auto cheepie so I can rule that out!!(:censored:) There were no mice or anything like that so I can rule that out also. A friend of mine found a way to test the injector coils with out pulling the plunum so Im going to try that and I am deff going to pull the plugs and see if I can get any clues there. Im also going to trow in a twist now to Before I filled up that other day I added a bottle of octane booster($2 for kicks and giggles) she had about 2-3 gallons left and It was almost perfect. soooo IDK. Tomarrow I will pull the plugs, and if I have time I will run the injector coil test.

Quote:

Originally Posted by tomtom72 (Post 119326)

Re: missing under load under 2k

Be very careful about back probing the ECM harness plugs. You will enlarge the female end of the connector if you use something like a test light probe. Use stranded wire so you can adjust the size to get a good connection without enlarging the female terminals. This caused much tracking down of intermittent faults in another member's car! Drove him nuts for quite a while.

You might as well just check the ohms on the plug wires and coils while you have the DVOM out of the tool box. You can ohm from plug wire thru the coil to the matching plug wire....I believe it should be in the 30k to 50k ohm range.

It could be that the octane booster dislodged some crud and it's fouling the tip of an injector? I doubt that that stuff did any actual harm to any fuel system parts....it's not like you used Moroso Octane Booster concentrate...do they even make that stuff any longer?

:cheers:
Tom

Re: missing under load under 2k

Jerry's recommendation about using silicone grease (dielectric) on each end of the plug wire boot and on the coil terminal fixed my miss that was similar, probably worse than yours.... Cheep fix!!!