2.3L Turbo hesitating and backfiring going up a hill - Ford Mustang Forum

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post #1 of 68 (permalink) Old 11-28-2016 Thread Starter
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2.3L Turbo hesitating and backfiring going up a hill

Hello, new to the forum here and looking for some 2.3L turbo help. Did a nice 1929 Ford Track build and put a 1988 2.3L Turbo from a thunderbird turbo coupe in it. Had everything installed professionally. I've put around 100 miles on it so far just puttering around town until I am comfortable enough to hit the highway with it. No issues with it until today as I started to climb a hill. The turbo just started to sputter as if it was running out of gas and was jerking, at the same time it started to backfire like fire crackers going off. It has never done this before. Luckily I had a road I was able to turn into quickly before it felt like the car was about to die. As I slowly turned left into the road, all went back to normal. I was only about a mile away from home so I kept it slow but no backfire. Any idea what could cause this to happen? Again, started going up a hill, car started hesitating and jerking as if wanting to die, and lots of backfiring until I turned left and slowly started moving. What could this be? TPS set to .94. Cleaned idle air control. Oil changed to 10w30 with zinc additive. Spark plugs are NGK set to .30. Thanks for any help

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post #2 of 68 (permalink) Old 11-28-2016
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Do a boost leak test. Sounds like you might be leaking somewhere when your under load and actually in boost. Tomorrow check if it does the same thing under more aggressive acceleration. If so I'd bet its a boost leak.


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post #3 of 68 (permalink) Old 11-28-2016 Thread Starter
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Ok I'll have to pick up a boost tester. Boost kicked in fine on the way home. Kind of weird. Would vacuum leak cause this?
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post #4 of 68 (permalink) Old 11-28-2016
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Wouldn't be under vacuum when under a load like climbing a hill, but on a turbo car a vacuum leak will be a boost leak. The only difference is if your actually creating boost, unless its pre turbo. I had an 88 T-Bird Turbo Coupe before I knew anything about turbo systems. It would drive just fine unless I tried to accelerate quickly or climb a hill. I sold that car for $500 because it had a boost leak. I didn't know. It would buck and cut out almost like the engine was cut off, and yes sometimes it would backfire a little. I thought it was an electronics issue. You might have a different issue but the first test you should do is a boost leak test. Other than the tester its probably going to be a free repair if its a boost leak.

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post #5 of 68 (permalink) Old 11-28-2016 Thread Starter
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Quote:
Originally Posted by blu13gt View Post
Wouldn't be under vacuum when under a load like climbing a hill, but on a turbo car a vacuum leak will be a boost leak. The only difference is if your actually creating boost, unless its pre turbo. I had an 88 T-Bird Turbo Coupe before I knew anything about turbo systems. It would drive just fine unless I tried to accelerate quickly or climb a hill. I sold that car for $500 because it had a boost leak. I didn't know. It would buck and cut out almost like the engine was cut off, and yes sometimes it would backfire a little. I thought it was an electronics issue. You might have a different issue but the first test you should do is a boost leak test. Other than the tester its probably going to be a free repair if its a boost leak.
Ya I have the hesitation issue as well, it doesn't pick up quickly but eventually kicks in. I just take it as being a 4 banger but you might be right, I may just be fighting a boost leak. I'm going to replace all the vacuum lines this weekend and get a boost tester. Just odd as it is the first time it has occurred. Thanks for the input and this is where I will start
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post #6 of 68 (permalink) Old 11-28-2016
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I would start with some basics, check fuel pressure under load. Make sure wires are not loose or disconnected; try gently pulling or wiggling wires, connectors etc, while engine is running.

You might be able to tell if a sensor has failed by checking codes from the ECU. On a conversion like yours, it will pull up some unrelated codes, but you might see something substantial.

Hesitation could be caused by an issue with the VAM, assuming you still have one, not an aftermarket system? Back firing could be a lean misfire, since it happens under a load. The VAM is a common culprit for this.

How do the spark plugs look? Could be a spark miss caused by a bad TFI module, another common culprit.

You might want to play with spark timing as well. It would be a good idea to see where the timing is set. The factory specs for ignition timing on 2.3's are super conservative (10-12 degrees BTDC) and leave a lot of throttle response and power behind at stock boost levels

Do you have a picture or 2 of the engine bay?

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post #7 of 68 (permalink) Old 11-28-2016 Thread Starter
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Quote:
Originally Posted by ohc230 View Post
I would start with some basics, check fuel pressure under load. Make sure wires are not loose or disconnected; try gently pulling or wiggling wires, connectors etc, while engine is running.

You might be able to tell if a sensor has failed by checking codes from the ECU. On a conversion like yours, it will pull up some unrelated codes, but you might see something substantial.

Hesitation could be caused by an issue with the VAM, assuming you still have one, not an aftermarket system? Back firing could be a lean misfire, since it happens under a load. The VAM is a common culprit for this.

How do the spark plugs look? Could be a spark miss caused by a bad TFI module, another common culprit.

You might want to play with spark timing as well. It would be a good idea to see where the timing is set. The factory specs for ignition timing on 2.3's are super conservative (10-12 degrees BTDC) and leave a lot of throttle response and power behind at stock boost levels

Do you have a picture or 2 of the engine bay?

Timing was set to 10 degrees BTDC. Spark plugs aren't terrible, have a little blackness to them but nothing out of the ordinary. It does still have the VAM and that could very well be it but I am not sure on how to test that. Here are some pics of the engine bay.
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post #8 of 68 (permalink) Old 11-29-2016
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OK, on the VAM;

-I suggest that you pop the plastic cover off of the meter. It is held in place by a thin bead of silicone. If you pry it gently, a little at a time, it will come off in one piece. See attached picture for more details on the VAM.

-Next, with the cap removed, you'll want to warm the engine up to operating temp, once warmed, with the engine running, adjust the idle speed up to 1500-1800 RPM, using the idle stop screw on the side of the throttle body.

-Next, take a look at the VAM. Inside of it you will see a small circuit board, a wiper arm and a plastic gear.

-With the engine running, gently push the wiper arm on the VAM, increasing and decreasing it's position slightly. when you do this, it will either lean or enrich the fuel mixture and you will notice a drop in RPM. If it does not affect RPM, it is highly likely that you have an issue with the VAM. If does affect RPM and mixture, note the position which enables the highest RPM. By now, you probably figured out by looking at it, that if you rotate the gear one direction or the other, you can change the fuel mixture, but right now we're interested in function.

10 degrees of initial spark is much lower than I recommend. It will give sluggish acceleration and poor throttle response & HP. My cars are set between 16-18 degrees.

Re-post after you try that and let us know what you found. If that doesn't shed some light, we'll move onto the some other things.

Nice looking car BTW.


...


89' Mustang convertible, high compression N/A 2.3.

85' SVO under s l o w deconstruction.

93' hatch currently under development


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post #9 of 68 (permalink) Old 11-30-2016 Thread Starter
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Quote:
Originally Posted by ohc230 View Post
OK, on the VAM;

-I suggest that you pop the plastic cover off of the meter. It is held in place by a thin bead of silicone. If you pry it gently, a little at a time, it will come off in one piece. See attached picture for more details on the VAM.

-Next, with the cap removed, you'll want to warm the engine up to operating temp, once warmed, with the engine running, adjust the idle speed up to 1500-1800 RPM, using the idle stop screw on the side of the throttle body.

-Next, take a look at the VAM. Inside of it you will see a small circuit board, a wiper arm and a plastic gear.

-With the engine running, gently push the wiper arm on the VAM, increasing and decreasing it's position slightly. when you do this, it will either lean or enrich the fuel mixture and you will notice a drop in RPM. If it does not affect RPM, it is highly likely that you have an issue with the VAM. If does affect RPM and mixture, note the position which enables the highest RPM. By now, you probably figured out by looking at it, that if you rotate the gear one direction or the other, you can change the fuel mixture, but right now we're interested in function.

10 degrees of initial spark is much lower than I recommend. It will give sluggish acceleration and poor throttle response & HP. My cars are set between 16-18 degrees.

Re-post after you try that and let us know what you found. If that doesn't shed some light, we'll move onto the some other things.

Nice looking car BTW.


...


Thanks OHC230, I am going to test the VAM on Saturday as well as do a Boost Leak Down test to see what I find. Will get back to you this weekend
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post #10 of 68 (permalink) Old 12-01-2016 Thread Starter
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Quote:
Originally Posted by ohc230 View Post
OK, on the VAM;

-I suggest that you pop the plastic cover off of the meter. It is held in place by a thin bead of silicone. If you pry it gently, a little at a time, it will come off in one piece. See attached picture for more details on the VAM.

-Next, with the cap removed, you'll want to warm the engine up to operating temp, once warmed, with the engine running, adjust the idle speed up to 1500-1800 RPM, using the idle stop screw on the side of the throttle body.

-Next, take a look at the VAM. Inside of it you will see a small circuit board, a wiper arm and a plastic gear.

-With the engine running, gently push the wiper arm on the VAM, increasing and decreasing it's position slightly. when you do this, it will either lean or enrich the fuel mixture and you will notice a drop in RPM. If it does not affect RPM, it is highly likely that you have an issue with the VAM. If does affect RPM and mixture, note the position which enables the highest RPM. By now, you probably figured out by looking at it, that if you rotate the gear one direction or the other, you can change the fuel mixture, but right now we're interested in function.

10 degrees of initial spark is much lower than I recommend. It will give sluggish acceleration and poor throttle response & HP. My cars are set between 16-18 degrees.

Re-post after you try that and let us know what you found. If that doesn't shed some light, we'll move onto the some other things.

Nice looking car BTW.


...

So had to take a couple days away from the build as I had a wheel bearing go out in my daily driver but back to it. I m going to boost test this weekend as well as check the VAM. A gremlin I had today was as I started the car after sitting for 4 days, she started fine and was sitting around 900 rpm. I blipped the throttle to see how the idle was doing and she stumbled and died. Tried to start back up with no luck. Start number 2 a little better but no go. Start 3 got her fired back up but she puffed out some white smoke but that went away pretty quick. I moved her into the garage and let her idle til she hit operating temps and i started blipping the throttle again, this time no issues and she was sitting around 1100 rpm. What could this have been? Would the MAF cause this? Thanks for all the help guys
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Wait do you have a MAF or a VAM? If you didn't wire one in and everything is stock then you have a VAM and need to test that

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post #12 of 68 (permalink) Old 12-02-2016 Thread Starter
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Wait do you have a MAF or a VAM? If you didn't wire one in and everything is stock then you have a VAM and need to test that
Sorry I meant VAM
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Did you get a chance to check the VAM?

Yes, it might cause the issue you're having but before we move onto other areas, I would make sense to check the VAM as I outlined first. There are a few more checks to do while you have the lid off the VAM.








--

89' Mustang convertible, high compression N/A 2.3.

85' SVO under s l o w deconstruction.

93' hatch currently under development


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post #14 of 68 (permalink) Old 12-02-2016 Thread Starter
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I got the VAM plastic head off last night, will do the check tonight and let you know what readings I get. I went ahead and picked up one off eBay for a backup just to put on the shelf if this one checks out
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If you have a volt /ohm meter, I have a short list of things you should check as well. The throttle position sensor is an easy one to check. I will post some info later, but as usual, this website is locking up and it won't allow me to type anything.


89' Mustang convertible, high compression N/A 2.3.

85' SVO under s l o w deconstruction.

93' hatch currently under development


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