So what does this mean?? 94 3.0L Low power
#16
08-26-2010, 07:22 PM
Fleet Mechanic
Figure out why the vacuum doesnt make any difference yet?
My 94 does the same thing runs rich, bad mileage, just started misssing at idle (could haved finally fouled a plug) and not going into closed loop.
Replaced the right side O2 sensor loosly based on some KOER codes. When I pulled it out it was a Bosch. Didnt help.
Also checked the MAF sensor- ok.
You can often fix the MAF sensor. Last year I took it apart and one of the two little wires was furry with carbon. Carefully brushed it off and presto.
The only reason I found the problem with the MAF was I noticed the miss changed when I tapped on it. Didnt even throw a MAF code.
I check the fuel pressure tomorrow.
The regulator just about gotta be bad in both cases- I think.
HTF did you get 17000 posts ? You gotta be 287 yo or have site admin privledges. I been posting at Meso Rx for 3 years and I have 1700 posts
And I`m into that stuff.
PLEASE post back her If you figgure this thing out.
I`ll do the same
My 94 does the same thing runs rich, bad mileage, just started misssing at idle (could haved finally fouled a plug) and not going into closed loop.
Replaced the right side O2 sensor loosly based on some KOER codes. When I pulled it out it was a Bosch. Didnt help.
Also checked the MAF sensor- ok.
You can often fix the MAF sensor. Last year I took it apart and one of the two little wires was furry with carbon. Carefully brushed it off and presto.
The only reason I found the problem with the MAF was I noticed the miss changed when I tapped on it. Didnt even throw a MAF code.
I check the fuel pressure tomorrow.
The regulator just about gotta be bad in both cases- I think.
HTF did you get 17000 posts ? You gotta be 287 yo or have site admin privledges. I been posting at Meso Rx for 3 years and I have 1700 posts
And I`m into that stuff.
PLEASE post back her If you figgure this thing out.
I`ll do the same
Pull the vacuum line of the fuel pressure regulator and see if there is a gas in it. there should not be gas in it. it is on the fuel rail
#17
08-27-2010, 07:41 AM
...
Here's what has been done so far.
NEW - cap, rotor, wires, plugs (Autolite AP104), fuel filter, O2 sensors, air filter, fresh fuel, cleaned MAF, IAC, no vacuum leaks detected, battery was dead has been charged to 13V. The fuel pump appears new and the screen is not clogged...
Here's what has been done so far.
NEW - cap, rotor, wires, plugs (Autolite AP104), fuel filter, O2 sensors, air filter, fresh fuel, cleaned MAF, IAC, no vacuum leaks detected, battery was dead has been charged to 13V. The fuel pump appears new and the screen is not clogged...
A number of folks, including me, have solved a loss of power problem by doing so.
I would also make sure the battery is up to snuff & holding a charge.
#18
08-27-2010, 04:38 PM
It ran ok this morning for a couple minutes till it warmed up then started missing and the check engine light came on. The fuel pressure (30-45psi) with key on and at idle was 30 and increased to 38 upon WOT. Pulling and blocking the fuel regulator vacuum line raised the pressure 8 psi. This shows that the regulator is ok. Vacuum drops with WOT.
It actually runs better without vacuum applied to the reg, which was the way it was befor I started working on it. I had plugged a non functional vacuum line to the reg last summer when I fixed the A/C and MAF !
Here`s what is happening:
Either the fuel pump is wimpy or the filter is clogged. Changed the filter last year. The low fuel pressure causes a lean mixture. But the HEGO reports O2 in the exhaust since there isnt enough fuel to use all the O2 in the charge. So the MCU increses the injector pulse width until the the O2 is completely consumed in the power stroke and so doesnt show up in the exhause stroke. So, in effect, the HEGO is determining the mixture after it warms up, and that aint good enough. So it runs rich and gets poor fuel economy. And has for years ! Can rule out fouled plugs since it runs ok when cold. If a plug is fouled it doesnt fire when cold or hot.
The whole thing started several years ago when the DEALER ONLY AVAILABLE central vacuum fitting bit the dust and I redesigned it.
The only remaining question is where did the unhooked vacuum line go befor I redid the vacuum lines? Its on the right side of engine and runs along side the fuel reg line and terminates beside it.
Btw, used a tiny artists camel hair brush to clean the MAF wire. Like the kiss of a butterfly.
It actually runs better without vacuum applied to the reg, which was the way it was befor I started working on it. I had plugged a non functional vacuum line to the reg last summer when I fixed the A/C and MAF !
Here`s what is happening:
Either the fuel pump is wimpy or the filter is clogged. Changed the filter last year. The low fuel pressure causes a lean mixture. But the HEGO reports O2 in the exhaust since there isnt enough fuel to use all the O2 in the charge. So the MCU increses the injector pulse width until the the O2 is completely consumed in the power stroke and so doesnt show up in the exhause stroke. So, in effect, the HEGO is determining the mixture after it warms up, and that aint good enough. So it runs rich and gets poor fuel economy. And has for years ! Can rule out fouled plugs since it runs ok when cold. If a plug is fouled it doesnt fire when cold or hot.
The whole thing started several years ago when the DEALER ONLY AVAILABLE central vacuum fitting bit the dust and I redesigned it.
The only remaining question is where did the unhooked vacuum line go befor I redid the vacuum lines? Its on the right side of engine and runs along side the fuel reg line and terminates beside it.
Btw, used a tiny artists camel hair brush to clean the MAF wire. Like the kiss of a butterfly.
#19
08-27-2010, 08:33 PM
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Pretty sure
FPR just needs vacuum from a tee near the back of the intake on all the Rangers I've had so far. Just a good source to run it. And make sure to buy good gas from a currently busy station that doesn't have a tanker there. THAT could cause some problems as you can easily get crud from bottom of stations' tanks. No matter what brand or assurances. Does your pump have the full voltage when it bogs out? Shoot, had 1 where that harness came unfastened & dragged on the driveshaft for a day or so.
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