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Author Topic: Random running issues  (Read 2804 times)

JThw8

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Random running issues
« on: May 25, 2011, 08:46:00 AM »
Every time I think Im getting somewhere with this car its a new setback.

So here's where it stands today

New cap, rotor, plugs and wires
New fuel filter
Cleaned all grounds at fuel pump and engine
Cleaned MAF and throttle body
Checked for vaccum leaks, so far haven't turned up any.
Bypassed FPS on the firewall

Here's the issues
1)Still has a random stumble.  It seems to come and go and is more prevalent when hard on the throttle.  It is definitely MUCH improved over when I started, its even liveable for now, but its a symptom.

2) After shutting it down it doesnt want to idle on restart.  2 or 3 restarts and hold the throttle at 2k for about 10 seconds and then it will hold idle.  This doesnt seem to matter if its hot or cold happens on any restart where more than 1 minute has passed since shutdown (sometimes less)

3) The idle seems high.  At best it's idling around 1000rpm but many times it will creep up and idle around 1250.

My thoughts thus far are faulty fuel pressure regulator or weak fuel pump.  Both a bit on the pricy side so Id rather not just throw parts at it without a little more to go on.

A few notes from the adventure so far.
Never trust anything.  There were recipts in the car for new cap, rotor, plugs and wires when I got it. Less than a year old.  I had already bought the parts so I decided to swap them out anyway.  The rotor that was in the car didnt fit right it seems and the plastic was rubbing and had filled the cap full of dust and crud from it falling apart.  Definite improvement with the new parts.  I dont know why but after the tune up my boost gauge works, I never saw boost on the gauge before but now its working.  It seems to start to build boost around 3k  is that correct?

Right now I can live with these issues for the rally if I have to, but it wont go through NJ inspection.  They couldnt get it to hold idle so they couldnt do emissions testing.  Even if I can convince them to let me get it to hold with a few restarts and holding the revs a few seconds I think the idle will be too high for the test.
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Gostlrs

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Random running issues
« Reply #1 on: May 25, 2011, 02:59:00 PM »
Idle Bypass Valve for you idle problems. I had same thing going on and that was it for me, Also throw a can of Berrymans B-12 Chemtool for fuel, can get it at walmart or any auto store. That stuff works wonders on the fuel system. It has cleared up a stuttering problems on 2 of my cars. Might need 2 treatments. Put the whole can in on a empty tank the fill up.
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JThw8

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Random running issues
« Reply #2 on: May 25, 2011, 03:31:00 PM »
Already running the chemtool through the system, could be partly responsible for the improvement.

Enlighten me more on the idle bypass valve.  Is this something I need to adjust or just replace?  Where is it located and what should I be doing to check it?

FWIW it was a fairly hot day here, just got home and it was cooler and I gave her a shot and she started cold and held idle (still a bit high) so Im not sure if temperature may play a factor.
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JThw8

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Random running issues
« Reply #3 on: May 27, 2011, 05:04:00 AM »
It was a good day for the Capri.

I pulled the IAC and cleaned it out as best I could.  Then I bit the bullet and swapped out the starter.  I figured even if it kept stalling if it would restart on the first turn of the key it would be less of an issue (old starter took about 10 tries to "catch")

Now it starts like it should.  It seems to be holding idle both hot and cold.  Its running without stumbling, overall Im happy!  

Still idling about 1100 rpm, if it can get through emissions testing that way then Im not going to mess with it.
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Rocketman

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    • 91 BPT AWD Capri & 1991 XR2
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Random running issues
« Reply #4 on: May 27, 2011, 03:55:00 PM »
On the throttlebody, looking at it from the front - on the right side there is a recessed hole, threaded. Down inside it is the idle setscrew. There may be a rubber or other type of cap preventing direct access to it. Turning it clockwise (in) will lower the idle.

See if this helps. The ignition timing will also affect idle, have you checked to make sure that is in spec? (8-12* BTDC)
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JThw8

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Random running issues
« Reply #5 on: May 27, 2011, 04:12:00 PM »
It passed e-check today so I'll leave sleeping dogs lie for now.  One week until rally time and I still have other more pressing issues to address.  

Once its back home I'll dig into it further but its definitely a different car than the one I limped in April
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