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2 years of torment!; timing issues?
Topic Started: May 30 2014, 12:58 PM (5,725 Views)
Coyote X


the way it revs up slow and stumbles when you floor it kind of makes it look like the throttle position switch is bad or out of adjustment. It is pretty easy to test just unplug it and check the wires based on the wiring diagram. At idle the idle switch should show 0 ohms and anything off idle it should read infinity. I think it also has a wide open switch that works the same way when the throttle is at wide open. If the idle switch is staying closed after the throttle is moved at all just adjust it so it opens up as soon as the throttle is moved.

I looked on the diagrams I have on my site and they show lt green-black and lt green-white are the two you measure across for the idle position. and lt green-black and lt green-yellow for the wide open position. just unplug the wires from the sensor and measure directly on the sensor based on where the wires plug into it.
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clarkdw


The bogging when punching the gas and not when slowly pushing it is a pretty solid indicator of no "accelerator pump" enrichment. Coyote X could be onto something with the throttle switch but I would be more inclined to look at the MAP sensor. It is responsible for the accelerator pump action from the ECM once the throttle is off idle. Driving along when you mash the throttle it causes the ECM to go very rich momentarily.

I have recreated much the same symptoms by putting a 1.5 quart bottle in the MAP sensor line next to the sensor. The bottle was intended to reduce the enrichment on acceleration trying for better mileage. Too big a bottle made it fall on its face like yours does and also caused an EGR code to be set. The ECM test for EGR uses the changes in the MAP sensor reading to determine whether there is flow in the EGR.
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Hanuman
"The Almighty Grounds Cleaner"

im leaning towards map sensor/wiring failing or o2 sensor/wiring failing.....your older metro has a throttle switch instead of a tps. instead of reading and giving a variable resistance to the computer for throttle position, it reads to spots...idle and full throttle....if it doesnt see one of those two....it assumes your on the gas peddle.

the problem occurs when warm.
may be a problem in the wiring harness somewhere.
warm wires expand......insulation chafes, wires get bend and break ect.

check and recheck map/ts/02.
then check there out puts at the pins to the computer.
but first...check the adjustment of your throttle switch.
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Hanuman
"The Almighty Grounds Cleaner"

clarkdw
Jun 7 2014, 11:05 PM
The bogging when punching the gas and not when slowly pushing it is a pretty solid indicator of no "accelerator pump" enrichment. Coyote X could be onto something with the throttle switch but I would be more inclined to look at the MAP sensor. It is responsible for the accelerator pump action from the ECM once the throttle is off idle. Driving along when you mash the throttle it causes the ECM to go very rich momentarily.

I have recreated much the same symptoms by putting a 1.5 quart bottle in the MAP sensor line next to the sensor. The bottle was intended to reduce the enrichment on acceleration trying for better mileage. Too big a bottle made it fall on its face like yours does and also caused an EGR code to be set. The ECM test for EGR uses the changes in the MAP sensor reading to determine whether there is flow in the EGR.
perhaps you have a vacuum leak in the restriction valve before the map sensor that shows itself after everything gets warm.......
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UncleBranton
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I seem to remember a recall for the MAP sensor for my 93' but mine had already failed and been replaced. What a pain that was. Mostly in my leg because the car would idel but if I stepped on the gas it would stall, if I eased on the gas it would go to a point but if I held the peddle down too long it would stall. So I had to keep easing on the gas every few seconds to keep up the rpm's and time my clutching to shift, man did I get some leg cramps before that got fixed.
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nixmixin
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I am not 100% I checked the MAP correctly but from the diy I found, it checks out. And, when I unplug it while the car is idling, the car dies.
I followed the procedures to the letter on calibrating the throttle switch and that checks out too. The o2 sensor is brand new.

How do I check the outputs at the pins of the computer? Do you mean for continuity? Seeking a failed wire/short?
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nixmixin
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So, I am on the side of the road with a dead car. I think I am out of gas. If I am, that means my mpg has dropped to 18!
I hear the fuel pump kick in when I turn the key for a few seconds, as it should. The clear in-line fuel filter isn't full like it usually is.
The exhaust was really strong smelling lately. I thought it was just because the cat was removed. Apparently it was just puking fuel.
Argh!
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nixmixin
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Since I had some time to kill waiting for my wife to come rescue me, I jumped on the Google to search more for the solution to my car. Then I found THIS... http://www.teamswift.net/viewtopic.php?t=25522
So I popped open the hood and pulled the vacuum line from the air filter housing that feeds into the lower port of the iac valve. Car is off so, I shouldn't be able to blow through. I try to blow through but cannot. That is supposed to be like that, right? Then I turned the key to the on position without the engine running. I try to blow again and now I can barely blow through? From how I understand this valve, it is a solenoid. So, it should be open or closed, not in between. My theory is that the signals and solenoid are functioning correctly but I have to either clean the valve or the spring I put in it is too strong for the electromagnet to fully open the valve. So, that means I need to replace or rebuild that damn thing again. Fingers are crossed that I found the answer....
Does anyone still sell NEW ones of these?
Edited by nixmixin, Jun 12 2014, 01:06 PM.
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nixmixin
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Well...added gas and got back on the road. 18 mpg! Crazy!
To rule out the iac, I just bypassed it entirely. no difference whatsoever. Still running CRAZY rich with the high steady idle....
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Coyote X


18 mpg would be hard for the computer to dump that much gas in at normal driving. Have you checked the fuel pressure and spray pattern of the injector? Point a timing light at the injector, rev it up and down slowly while watching the spray pattern it should be a nice even fan pattern.

I think the computer is working like it should since every sensor has been checked over. It has to be in the fuel supply somewhere. Maybe the return line is clogged? Should be able to blow through it and hear bubbles out the gas cap. If no bubbles maybe it is swapped with the vent line? Check the vent line on the carbon can for bubble sounds and swap them if it has them. Maybe the fuel pressure regulator is bad? It is dumping in lot of fuel in somehow and I just don't see the computer making it dump that much so I'm now leaning towards a mechanical problem in the fuel.
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lnardozi
New Member
[ *  * ]
My car was using too much gas, so I went to the auto parts and bought a cheap tire stem and whittled the end down until it would fit in the return line. Then I drove to the gas station, took the return line loose from the throttle body, jammed the stem in there and attached it to their air line. The pressure went (by the gauge) over 80psi and then finally dropped to 0. Problem solved! Couldn't possibly be your problem after 6 pages of experts, but on the other hand, it only cost me $1.78 to try it.
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Old Man


lnardozi
Jun 12 2014, 07:52 PM
My car was using too much gas, so I went to the auto parts and bought a cheap tire stem and whittled the end down until it would fit in the return line. Then I drove to the gas station, took the return line loose from the throttle body, jammed the stem in there and attached it to their air line. The pressure went (by the gauge) over 80psi and then finally dropped to 0. Problem solved! Couldn't possibly be your problem after 6 pages of experts, but on the other hand, it only cost me $1.78 to try it.
Check out my post #3. I said to check the fuel system first thing.
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Hanuman
"The Almighty Grounds Cleaner"

i have gotten 18 mpg before on my old 92 metro. burned valve. my compression was 18, 60, 150.

just for shits and giggles.....
when the engine gets warmed and is running like crap......do a real fast dry compression test and post the numbers along with your cold numbers.

why? quick easy way to eliminate any odd valve issues.....like a hydrualic lifter that is pumping up to much when warm leaving a valve open....who knows?

also.....lets see that fuel pressure while running?
do your spark plugs have the threaded part on top that can be unscrewed?....had those come loose on a subaru...ran poor
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nixmixin
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ok. got her home and did some things....
I remember when I did the throttle body rebuild, that I didn't take apart the fast idle air valve and read that it could cause similar symptoms. So, off came the throttle body again. Sure enough, it was hella nasty and crusty with carbon build up. I pulled it apart, cleaned it up and started a pot of water on the stove. Calibrated the wax expansion valve at around 180 degrees. Valve closes when hot and wide open when cold now. Used a piece of hose to test the blow through. All is good. Put everything back together... ran even worse and would barely even idle!!! But then I remembered that my cam sprocket alignment mark was off by a tooth and I hadn't moved it yet. So, I put it back to where it once was. Started right up... idled waaaay smoother. After it warmed up, the idle dropped back down to around 900. Improvement!!! Then I stabbed the gas... still does the bog thing.... ARGH!! It is better than it has been lately though just not 100 % yet. It definitely isn't AS rich as earlier but still running rich. I was also finally able to set the timing without being maxed out on the distributor!!! Set it at 8 DBTDC.

During today's wrenching, I reconnected the IACV. That thing is hissing something bad now. I think the spring is too strong for it.

Tomorrow's list:
compression tests - warm vs cold
fuel pressure test
I blew out all the fuel lines last week but I will try the blowing into the return and having someone listen to the open gas tank for bubbles to confirm that the line is clear.
When I rebuilt the head in February, I replaced all the lifters with brand new ones.
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nixmixin
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Just wanted to add that I have the idle adjustment screw at 3/4 turn back out from all the way in. (if that makes since). I am sure I can turn and bring the idle down more now. But first I want to get the bogging gone.
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