this is an on going thread from an old one I couldn't find to add to but heres the deal.

 

Put new head gaskets on my 87 XT (non turbo). Car was running fine before pulling the heads. Ok so it took me 4 months to finish the job, but when it went back together it starts and runs (idles) fine....until you put a timing light on it. Light is perfect...except for a random 20 degree ATDC firing. You rev it up and you get a good solid miss/major hesitation with any throttle input. This "missfire" is also noted on the tach inside the car (needle jumps). Swapped out the cap with a spare and it still does it. Swapped out the rotor with a new one and it still does it. Distributor shaft feels solid (no play).

 

what am I missing here guys?

 

Bill

Are you checking the timing with the green test connectors hooked up?

 

Are you sure the knock sensor is hooked up?

Are you checking the timing with the green test connectors hooked up?

 

Are you sure the knock sensor is hooked up?

 

does it with or without the green connectors hooked up

 

Knock sensor is where...I hooked up all the leads but who knows...

 

Bill

but when it went back together it starts and runs (idles) fine....until you put a timing light on it. Light is perfect...except for a random 20 degree ATDC firing.

 

This is what's confusing me. The timing is SUPPOSED to be at 20 deg Btdc. Sure you're 20 After?

This is what's confusing me. The timing is SUPPOSED to be at 20 deg Btdc. Sure you're 20 After?

 

sorry...thats with my timing light set at 20...reality is its set at 20 BTDC with a random firing at TDC

 

Bill

If it's non-turbo, it wouldn't have a knock sensor, don't bother looking. I would check to see if you have any check engine codes first, and see what you get. Also, the timing should be set and checked with the test mode connectors connected. Let us know what you get.

Do they still have a centrifugal advance in the distributor? If so, i had a spring fall off one of the arms of the one in my ea81t a while back, caused similar symptoms....

I think 86's were vacuum advance, but an '87 should have a Crank Angle Sensor in the distributor. The advance is controlled by the ECU.

87 was a split year, espescially for XTs. Does the car in question have a Flapper MAF or a Hot wire?

 

If it's a flapper then there will be a vaccum advance on the distributor, as well as a mechanical weight advance in the base. I had trouble passing emissions because of those weight sticking. It also WILL have a knock sensor. Because ignition is controlled independant of the ECU by the Knock Control unit.

87 was a split year, especially for XTs. Does the car in question have a Flapper MAF or a Hot wire?

 

If it's a flapper then there will be a vacuum advance on the distributor, as well as a mechanical weight advance in the base. I had trouble passing emissions because of those weight sticking. It also WILL have a knock sensor. Because ignition is controlled independent of the ECU by the Knock Control unit.

 

lets see if I can cover everyone

 

timing is set at 20 BTDC with green connectors connected. Timing "jumps" weither they are connected or not. No vacuum diaphragm no mechanical advance - has the star wheel. BUT also has an MAF w/flapper...go figure.

 

I'd really like to try and figure out how to read codes on this thing - someone want to tell me if it has that capability?

 

Bill

lets see if I can cover everyone

 

timing is set at 20 BTDC with green connectors connected. Timing "jumps" weither they are connected or not. No vacuum diaphragm no mechanical advance - has the star wheel. BUT also has an MAF w/flapper...go figure.

 

I'd really like to try and figure out how to read codes on this thing - someone want to tell me if it has that capability?

 

Bill

 

Okay, you have a Flapper MAF. After further looking in FSMs it seems I was wrong about a knock sensor, I was sure all early MPFI had them, but apperantly not.

 

At any rate If you don't have a a knock control unit something must control the advance. You're distibutor look anything like this?

 

Even if you're model does not have a vaccuum advance, I'm betting that it surely till has mechanical weights. These early systems have no Cam or crank angle senor, so would not be possible for the ECU to control timing. There must be a vacuum or/and mechanical advance. You would have to dissassemble the disty a bit to see the weights.

Okay, you have a Flapper MAF. After further looking in FSMs it seems I was wrong about a knock sensor, I was sure all early MPFI had them, but apperantly not.

 

At any rate If you don't have a a knock control unit something must control the advance. You're distibutor look anything like this?

 

Even if you're model does not have a vaccuum advance, I'm betting that it surely till has mechanical weights. These early systems have no Cam or crank angle senor, so would not be possible for the ECU to control timing. There must be a vacuum or/and mechanical advance. You would have to dissassemble the disty a bit to see the weights.

 

Nope...

 

just the star wheel and sensor inside. No weights, springs, or anything else... I went in there to see / clean the sensor or wheel.

 

Bill

O yeah, reading codes!

 

the short of it

 

There is a LED light in the front of the ECU. Pull the lower dash panel, driver side, it's bolted to the steering column. this is the light to read the codes from.

 

To read past codes:

 

Plug in only the 2 black connectors. turn key to on, light will flash long blips for the 10's column, and short ones for the ones. 3 long+2 short + code 32, etc..

 

Reading the past codes can be a good way to diagnos intermittent problems caused by poor connections. The problem may not happen during active code test, but will be stored from the "momentary" malfunction last time you hit a big bump or there was moisture.

 

To read current codes

 

Plug in only the green connectors. Turn key to on. Fuel pump should cycle in time with the CEL light flashing. press gaspedal all the way down, then back to half, hold for 2 sec. then start the car. Run engine over 2000 rpms for 40 sec. Drive forward and back in a straight line for just a few feet(try to get over 1 mph) Eventually the CEL will either blink continuosly(nothing wrong) or it will light up(code present) now read the code being outputed by the LED on the ECU

 

To clear codes

 

Plug in both sets of connectors. turn key on, press gas pedal all the way down, then back to half, hold for 2 sec. then start the car. Run engine over 2000 rpms for 40 sec. CEL will blink then go off if no codes are detected.

 

This is useful for after repairs. Clear the codes, take her for a drive, then check for new codes if there is any trouble.

Nope...

 

just the star wheel and sensor inside. No weights, springs, or anything else... I went in there to see / clean the sensor or wheel.

 

Bill

 

NAHHH, there must be weight in there. Otherwise you have static timing. This is not a CAS system. You may have to remove the disty, punch out the roll pin that holds the drive gear on, and slide the whole shaft up out to get ot it.

 

What do the wiring connections for it look like? just 2 wires that bolt to the coil? or four wires in a connector, plugged into the harness?

NAHHH, there must be weight in there. Otherwise you have static timing. This is not a CAS system. You may have to remove the disty, punch out the roll pin that holds the drive gear on, and slide the whole shaft up out to get ot it.

 

What do the wiring connections for it look like? just 2 wires that bolt to the coil? or four wires in a connector, plugged into the harness?

 

2 wires to the coil, 4 wires to the Dist.

the flapper style xt had weights and vac advance. when mine died i replaced it with a carbureted ea82 disty, same stuff. otherwise thats your problem, you have the wrong disty. part number 21 in that diagram hides it all

2 wires to the coil, 4 wires to the Dist.

 

This is the one shown for MPFI Turbo. Not the one listed for non-turbo but sounds like what you are describing wire wise. But even this disty has Vac advance and weights

the flapper style xt had weights and vac advance. when mine died i replaced it with a carbureted ea82 disty, same stuff. otherwise thats your problem, you have the wrong disty. part number 21 in that diagram hides it all

 

weeel, its the same dist. thats been in the car for 156,000 miles. Has the 4 prong black plug on it. I didn't pull the star wheel so maybe there is a weight under that but the pickup thats in the diagram is totally different than what I have. Pick up is about 1/2 thick and about an inch long. There is no vacuum advance diaphram...I'll take a picture when I get home

 

Bill

I dont know if this will help, but when my ea82 wagon had this problem it was because of teeth getting striped off the belts because of a bad bearing in the idler pulley. I had just replaced them too. just a thought.

just got home and ...ok my bad...

 

its not an MAF...its the "wire" as you said so that explains the later dist.

 

Bill

Gloyale, I didn't mean to doubt you on anything, in fact I stand corrected on most of it,haha. I'll leave this one to you. For some reason I thought these had the CAS distributor, sorry for the wrong info!

Being that you have a CAS distribitor - it's not likely your problem. The ECU controls the timing based on sensor input.

 

So now you need to make sure you have the thing set into test mode to check the timing.

 

GD

Being that you have a CAS distribitor - it's not likely your problem. The ECU controls the timing based on sensor input.

 

So now you need to make sure you have the thing set into test mode to check the timing.

 

GD

 

As I said before, it doesn't matter if the green connector is hooked up or not. The timing jumps either way. It is evident with the timing light, AND on the tach inside the car. So far it has always beed iratic and only 20 degrees (from 20 BTDC to TDC)

Also present is a significant hesitation to the point that if you leave you foot in it it will die.

 

Bill

I'm very rusty in reference to the EA82T

so please forgive any mis - information.

but

the timing on this engine can only be set when

 

1) The idlle switch is on (this is located in the TPS)

and

2) the green connectors are connected

 

Since you mention a throttle on problem also

I would look into testing the TPS.

Hope this helps.

 

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ok...heres where we're at.

 

Tried reading codes today. 5 flashes...5 flashes...5 flashes... (O2 sensor light)

 

thats either a 5 or a 55 but in either case my factory shop manual doesn't have either one.

 

anyone with ideas?

 

Oh...

 

and I've narrowed it down to a warmed up problem. Cold it runs fine. Warm its like you unplugged the TPS but its running real rich. If this were a Jag I'd be doing a capacitor in the AFM harness trick right now....

 

Bill