94 Subaru loyale stumbles on acceleration

[rybike13]

       Well after owning my car for a little over a year it developed a leaky head gasket. I decided it was time to reseal the motor and try to make it run like as good as new, ever since the day I bought the car it has stumbled under 3000 rmp and hesitates throughout the rpm range. I know these motors have there weaknesses and are not very powerful so im not expecting a lot just something more drivable.

 

       My car is a 94 loyale wagon 5 speed push button 4wd and ea82 spfi it has 170,000kms (100,000miles) The recent parts i have put into my car where, Head gasket, rear main, clutch, valve stem seals, cam seals, valve cover seals, intake manifold gasket, throttle body rebuild, thermostat, coolant temp sensor, pcv valve, air filter, fuel filter, cap, rotor, plug wires and spark plugs.

 

       The timing was set and the motor was put back in the car, everything plugged in and filled up with fluids. I gutted the cat before reinstalling with new exhaust gaskets and was ready to do my first test run. After the car was warm and all the fluids levelled off it seemed it be running the same as before just with out the mess, so fired it up again to set the distributor timing it was a little bit retarded but nothing crazy so set it to 20btdc. The car ran the same maybe a little smother idle but nothing fantastic, Being a little confused now on where the problem was coming from we decided to test my maf sensor and the tps both checked in with factory specs now im not sure where to go I don't really think my fuel system is the issu if any thing my motor seems to be running rich.  

 

       Im at the point where im about to take it to a professional mechanic, I didn't really want to create a new post when there is so much info out there already but im getting close to the end of my technical now how and i need some guidance. Is there anything ive missed? should i be looking deeper into my fuel system? or should i just take it to a mechanic to see what they have to say?

 

Any input will be much appreciated hopefully someone will be able to spot something ive missed

 

Thanks Ryan.         

[l75eya]

Throttle position sensor. Tps. Search about that. That's my guess.

[rybike13]

Ive tested it with a voltmeter and it all seemed to be within spec, I dont really want to order a new tps because of the price and loyales in my area are few and far between. I guess ill just have to keep an eye out looking for one in better shape than mine

[Dee2]

does the engine ever backfire ?

[86 Wonder Wedge]

Have you checked for play in the distributor and/or rotor shaft?

 

Also check for any AC voltage present in the system. This will also cause havok in the system.

[rybike13]

Well I have been able to do some more work on my car over the past weeks, I did some messing with my distributor timing by moving what tooth the gear sat on at tdc. Every position other than my original marks made the engine back fire or not start at all so went back to original there is no play on the disty shaft and my rotor is new. I did look around for ac current under my hood and didn't see anything. Car idles nice but at 3/4 throttle it cuts out and wont go over 3000 rpm under load.

 

Next I did a vacuum test it showed about 18 in (3000 ft) with a steady fluctuation of about one or 2in, if i rev it up to 2500 and let go of the throttle it goes down under 5in at rev then up to 20 after i let off. I did a compression test as well with 125 in 1-2-3 and 135 in 4 and my spark plugs where all dry and white  

 

Thinking its running lean and its not getting enough fuel I decided to replace the fuel pump, it now revs up to 3000 a little quicker but still dies out.

 

I did end up driving it back into town from my buddies whee ive been working on it, its only about 10k on a highway into town if i shift my car before 3000 it accelerates smooth but once I hit 5th gear I was only doing about 70km/h, agitating the pedal as much as I could I just managed to get it up to 3100 and maybe doing 80km/h before doing the over haul I got a speeding ticked clocked at 125km/h my car is not a race car but at least i wasn't worried about getting a ticket for going to slow before, I guess i'm not sure where to go at this point any advice would be greatly appreciated

 

Thanks Ryan  

[Dee2]

It doesn't sound like a timing problem but does sound like a fuel problem.  Too much air and not enough fuel.  Possibly dirty fuel injector(s).

 

From google I found:

 

Other problems that cause acceleration stumble include vacuum leaks, low
fuel pressure, a weak spark caused by low coil voltage or bad coil(s),
retarded ignition timing, and contaminated gas.

[86 Wonder Wedge]

Well I have been able to do some more work on my car over the past weeks, I did some messing with my distributor timing by moving what tooth the gear sat on at tdc. Every position other than my original marks made the engine back fire or not start at all so went back to original there is no play on the disty shaft and my rotor is new. I did look around for ac current under my hood and didn't see anything. Car idles nice but at 3/4 throttle it cuts out and wont go over 3000 rpm under load.

 

Next I did a vacuum test it showed about 18 in (3000 ft) with a steady fluctuation of about one or 2in, if i rev it up to 2500 and let go of the throttle it goes down under 5in at rev then up to 20 after i let off. I did a compression test as well with 125 in 1-2-3 and 135 in 4 and my spark plugs where all dry and white  

 

Thinking its running lean and its not getting enough fuel I decided to replace the fuel pump, it now revs up to 3000 a little quicker but still dies out.

 

I did end up driving it back into town from my buddies whee ive been working on it, its only about 10k on a highway into town if i shift my car before 3000 it accelerates smooth but once I hit 5th gear I was only doing about 70km/h, agitating the pedal as much as I could I just managed to get it up to 3100 and maybe doing 80km/h before doing the over haul I got a speeding ticked clocked at 125km/h my car is not a race car but at least i wasn't worried about getting a ticket for going to slow before, I guess i'm not sure where to go at this point any advice would be greatly appreciated

 

Thanks Ryan  

 

Ryan,

 

by AC current, I meant taking a DVM (digital volt meter) to the battery, set it in AC Volts mode, and see if it reads anything. Even 0.5VAC will throw the ECU off. I had this same problem in mine when my alternator was dying.

[rdweninger]

One thing to try, quick and easy... spray carb cleaner around any vacuum ports/connections.   I know you checked engine vacuum... but this tests for any vacuum leaks.   Rule out any vacuum leaks... first.