Running Rich and idle problems

[M.Dub]

you could check the cam timing.

If this was a problem would it be able to effect the cylinders individually or would they all be misfiring together at all times?

Thanks

[jonbill]

you could check the cam timing.

If this was a problem would it be able to effect the cylinders individually or would they all be misfiring together at all times?

Thanks

they are all misfiring aren't they? other variations (valve clearance?) might account for why 2 cylinders misfire more than others.

[M.Dub]

Yes they are, 1+2 pretty much all the time but cylinder 3+4 much less often.

 

[Carolyn]

I haven't done either of those, Iv never done anything like that and don't really have a clue how to do it.

Is it something I could do myself with some Googling? Are they difficult to do?

Firstly, I'd wait until the injectors arrive and see if they cure the problem.  If not:

Take a look at:

https://www.mr2roc.org/forum/index.php?topic=66483.0

Don't worry about actually removing cams, you don't need to do that.  The first part of the instructions has excellent photos that will show you how to remove the cam cover and check the cam timing. 

Decide if that's a job you want to tackle.  If you do:

Feeler gauges can be had from your local parts shop.  They are cheap get two sets of metric ones.

The last picture shows the position the cam lobes should be in (on cyinder #1) to measure the clearances. The inlet valves (the cam with the big hub on one end) should be in the range of .15 to .25 mm.  Select a .2mm feeler gauge and try to slide it under the cam (between the cam lobe and the flat steel bit below the lobe).  The exhaust clearances should be in the range of .25 to .35 mm. Select a .3mm gauge and try to slide it in.

If a gauge will not slide in, select a thinner one (.15mm for inlet and .25mm for exhaust) and see if they slide in. If they don't, the gaps are too tight they will prevent the valves from closing properly when the engine is warm. 

The feeler gauge should be a snug sliding fit in the gap. If the gauge is very loose, try thicker gauges to estimate the gap.  I doubt big gaps will be your problem, as the valves would be very noisy.

To measure the rest of the clearances, rotate the engine to bring both cam lobes up on the cylinder you want to measure next.

If you Do have tight valves, see below.  Decide if THAT'S a job you want to tackle (I recommend against it).  It might be time to get a decent mechanic involved.

Further pictures and instructions can be seen at:

https://www.mr2roc.org/forum/index.php?topic=65009.0

While you're in there, it pays to replace the cam cover gasket.  Don't buy a super cheap one!

[Beachbum957]

I have been following this thread as I sometimes get a random misfire code and may have missed a few things, but it looks like you have checked almost everything that is listed in the shop manual.  It might be a good idea to get a scan tool that gives actual values, not just codes and verify the values for coolant temperatures, RPM, and fuel trims look correct.  Fuel trims will give a good indication of the performance of the injectors and even the O2 sensors

But a commonly overlooked item is the crankshaft position sensor.  Normally, if it fails the problems are more severe, but the possibility of a weak signal (or loose connection) has been covered previously on the forum and in numerous articles.  Here are some links

https://www.mr2roc.org/forum/index.php?topic=47813.msg554334#msg554334

https://www.mr2roc.org/forum/index.php?topic=14573.msg181048#msg181048

https://www.underhoodservice.com/misfire-crankshaft-camshaft/

https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-crankshaft-position-sensor

Since the engine was out and rebuilt, verify the sensor is properly installed and the connections are tight.  A less likely possibility is a camshaft position sensor.  The manual has resistance values for both, so it is possible to do a basic check with a multimeter.

Crankshaft Sensor 1,630 ohm – 2,740 ohm cold, 2,065 ohm – 3,225 ohm hot
Camshaft sensor 835 ohm – 1,400 ohm cold, 1,0600 ohm – 1,645 ohm hot

Throwing parts at a problem can get really expensive, but many shop manuals have the same advice on testing electronic components "replace with known good parts".  If the sensors seem out of range or are suspect, perhaps someone has some you can try without buying new.

[M.Dub]

Thanks for the advice I know it's been a long thread. I'll try the injectors once I get them and then see how brave I feel if they don't work.

[shnazzle]

Thanks for the advice I know it's been a long thread. I'll try the injectors once I get them and then see how brave I feel if they don't work.

Don't feel bad. Rather this thread go on for 10 more pages and end up in a positive result than you going quiet, not having a running car and us left in wonder


And as they always say... You're never going to be the only one with this question so it's worth it. 

Wrt the valve job, I did the measuring in about an hour and the actual valve job in a parking lot with the help of Carolyn at our last national day

[M.Dub]

Hi all,

Just a quick update, I installed the replacement injectors from MAG and so far managed 60 miles of misfire free driving.

I'm still not overly confident this will last but so far so good.

Thanks for all the help.

[Carolyn]

It will be fine.  You figured it out and got the result!