Hesitation shuffle

[yewman]

My legacy 2 litre has just started to be really sluggish between 1750 and 2400 rpm, after which it goes like a train. It,s like there was a booster switch, as soon as the needle reaches 2400, off it goes.

 

The engine is smooth even when sluggish. No misfires or anything obvious. Performance above 2400 is superb.

Any ideas guys?

 

Yewman

[jamal]

are there any stored codes? My car would flash a CEL occasionally but hesitated all the time at low rpm. I had a stored knock sensor code that would come back when I reset the ecu. So yeah, replacing that sensor fixed things.

 

Also things like the fuel filter, plugs, and wires should be checked.

[ericem]

My legacy 2 litre has just started to be really sluggish between 1750 and 2400 rpm, after which it goes like a train. It,s like there was a booster switch, as soon as the needle reaches 2400, off it goes.

 

The engine is smooth even when sluggish. No misfires or anything obvious. Performance above 2400 is superb.

Any ideas guys?

 

Yewman

isnt that a turbo engine? Isnt that called turbo lag? What year? Non turbo, turbo? Year? Mileage?

 

but definitly replace little things, like spark plugs, oil, air filter for sure , and fuel filter, if all those check out, maybe u should reset the ECU.( or wait reset the ECU first lol)

 

Acually, my legacy was sluggish and beleive it or not ,i changeed the PCV valve, and its was WAY quicker off the line, and no vibration off the engine, but ur engine runs smooth.

[Manarius]

I'm going with Knock Sensor on this one as well. My friend's 97 2.2 was sluggish in the same window when the knock sensor was toast. After it was replaced, the car drove tons better.

[porcupine73]

Had similar issue here in a '96 and knock sensor fixed it.

[Setright]

Yewman, get under the dash, look for two sets of unconnected electrical connectors. One pair green, the other black.

 

Ignition OFF, connect black connectors. Ignition to ON. If the Check Engine light flashes a cycle of two long and two short pulses, that's code 22 - Knock sensor.

 

 

Otherwise, you could just have poured some contaminated petrol in there? Recently my car was hesistating at three different marks on the rev counter and I traced it to bad fuel. Bought 98 RON at a garage that doesn't sell much of the stuff and was probably "old" - meaning diluted with water and the like.

[yewman]

Thanks for all the helpful advice.

I'll answer the questions together.

The car is a 1999 GL estate, 2 litre non-turbo with 130,000 miles on the clock.

The plugs, leads and filters are all good.

I presume I can't check for stored codes or reset the ECU without going to the dealer.

What and where is the PCV valve?

It sounds as if the knock sensor is gone, but wouldn't the engine knock under power?

I,ll try Setright's idea if I can find the right leads.Hope I don,t cook anything by mistake.

Thanks Yewman..

[jonfit04]

Yewman, get under the dash, look for two sets of unconnected electrical connectors. One pair green, the other black.

 

Ignition OFF, connect black connectors. Ignition to ON. If the Check Engine light flashes a cycle of two long and two short pulses, that's code 22 - Knock sensor.

 

 

Otherwise, you could just have poured some contaminated petrol in there? Recently my car was hesistating at three different marks on the rev counter and I traced it to bad fuel. Bought 98 RON at a garage that doesn't sell much of the stuff and was probably "old" - meaning diluted with water and the like.

Quick Question. What does the pair of green connectors go to? I got under my dash and saw them, was just curious as to what they are?

Thanks

Jon

[Manarius]

Quick Question. What does the pair of green connectors go to? I got under my dash and saw them, was just curious as to what they are?

Thanks

Jon

You have a 99. Any sort of engine code reading information is irrelevant unless you have an OBDII reader. The connectors under the dash will do nothing.

[porcupine73]

If the knock sensor is gone, like to the point where the check engine light comes on because of it, you almost certainly will not get knock because the ECU pulls maximum timing as a 'failsafe' but you lose power. If it's just getting overly sensitive or it's cracked then again you probably won't get knock either because it's output signal may start looking like knock all the time so ECU pulls timing in this case too.

[jonfit04]

You have a 99. Any sort of engine code reading information is irrelevant unless you have an OBDII reader. The connectors under the dash will do nothing.

So I take it those connectors are for reading codes? I was just curious what they were for. Thanks:grin:

[yewman]

Yewman, get under the dash, look for two sets of unconnected electrical connectors. One pair green, the other black.

 

Ignition OFF, connect black connectors. Ignition to ON. If the Check Engine light flashes a cycle of two long and two short pulses, that's code 22 - Knock sensor.

 

 

OK, I connected the black connectors together, and switched on..2 long pulses and 3 short pulses came up on the engine check light.

Just to be sure I repeated twice more, same result.

 

I guess this is fault 23?? what is that?

 

Regards Yewman

[Setright]

Code 23 : Airflow sensor.

Circuit is open or shorted.

 

Try disconnecting the cable on you MAF (On or behind the air filter box) and spray some electronics cleaning fluid in there. Let dry, re-connect. Hope for a good connection.

 

Otherwise it may be time to replace the MAF

[Manarius]

Umm..are we forgetting that it's a 99? OBDII codes do not mean the same things as OBDI codes. Or, perhaps his car is so mucked that it has an OBDI system in it? Because that completely defies its year.

[yewman]

The car has full service history, looks like only routine work on the engine,cam belts and such. Everything looks original in the engine bay. You can tell if wrong bits have been fitted as the installation never looks as neat as a new one .

Is it possible UK spec is different?

 

Also where is the pcv valve mentioned in previous posts?

 

Meantime I,ll check the airflow valve.

 

Regards Yewman

[Setright]

Manarius, this is a European model. It'll have both the OBDII multi-pin port, as well as the plain old OBDI system and codes.

 

My MY2000 Impreza is identical in engine and ECU.

 

Even the latest Subes have the green diagnostic connector. It's a simple, easy access short cut. Useful on for road side diagnosis and such.

[Manarius]

Manarius, this is a European model. It'll have both the OBDII multi-pin port, as well as the plain old OBDI system and codes.

 

My MY2000 Impreza is identical in engine and ECU.

 

Even the latest Subes have the green diagnostic connector. It's a simple, easy access short cut. Useful on for road side diagnosis and such.

Interesting tidbit. Another reason why EDM > USDM

[yewman]

This is just an interim report.I found the air flow sensor, bolted on the engine side of the air filter. The connectors looked bright and clean, so I worked the plug in and out of the socket to ensure good contact. Also removed the airpipe with sensor attached. the two filaments hanging down in the airflow looked sound, although I have never looked before!

 

Initially the problem was the same, but has now disappeared. Two short trips and still OK. Was working today but tomorrow I will connect the wires under the dash and see if I get a code.

 

Message to Manarius, uk subarus may be a different spec , but they are expensive compared to other makes, and the prices for genuine parts are in wonderland, as are the dealer labour rates.

If I need to replace the airflow sensor, I will probably have to sell my house!

See you tomorrow, yewman

[Setright]

Yewman, you must reset the ECU code memory.

 

Connect both green and black. Ignition to ON. [Various relays will click and maybe your cooling fan will cycle on and off] Throttle pedal to the floor. Lift pedal up to about half travel, hold for two seconds, release pedal fully. Start the engine and drive away. Pretty soon the Check Engine light will either flash steadily indicating the memory is cleared, OR it will flash an error code if the fault remains.

[yewman]

Thanks for that advice, I'll try it out as soon as I can.

 

Is there any way of checking the correct function of the sensor with a meter? Presumably it gives a variable resistance in different air flows.

My sensor has 4 wires attached.

Regards Yewman

[porcupine73]

I think two of those wires are for power for the heated wire and the other two are for the sensor wire. The ECU knows the intake air temp and stuff and then can tell the mass of air passing by reading the sensor wire. With a meter I don't know if the user could tell whether the output signal is correct though.

[Setright]

I have access to the dealers tech manuals. I 'll cop a butchers.

 

In the mean time, you could try running the car without the MAF connected and see how it reacts?

 

To be certain of the error code. Reset the ECU, start the engine with MAF disconnected. Switch off, read error codes. 23 should come up again.

[forester2002s]

I 'll cop a butchers.

 

And I'll doff my titfer to you!

[Richard1296]

Huh ???

[yewman]

I've just done setright's test. Connect black wires and green wires,and the engine light has steady on and off flash, indicating fault cleared.

Well done everyone!

On the basis that it may come back, It would be interesting to know what info is in the manual.

 

Msge to Richard it,s Cockney ryming slang titfor tat= hat apples and pears= stairs

 

Regards Yewman