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2.3L Turbo hesitating and backfiring going up a hill

16K views 67 replies 5 participants last post by  Stustu07 
#1 ·
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
 
#2 ·
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.
 
#4 ·
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.
 
#5 ·
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
 
#6 ·
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?
 
#7 ·
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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#8 ·
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.


...

 
#9 ·
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
 
#13 ·
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.








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#15 ·
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.
 
#16 ·
I have it set to .94 volts and it sweeps with no breaks with the throttle to around 4.5 volts. I do have an extra one of those on hand as well. I also cleaned the IAC out pretty well and installed the plate to minimize the runaway idle but I also have a new one of those as back up as well. I may switch out those this weekend to see if it helps. Other than the VAM, I'm not sure what it could be now. I'm gonna replace the plugs this weekend as well as the Temp Sensors.
 
#18 ·
So did the VAM check, it causes the RPMs to lower if I push it both ways, I can also see it slightly moving in guessing figuring out the best idle. Seems like the VAM is good?
I went ahead and reset my base idle and reset my tps to .94, I will take her for a spin in the morning, what else should I check?
 
#19 ·
Ok so did the VAM check and it did lower RPM as I pushed it either way so guessing it is working fine? I also noticed it slowly moving I'm guessing trying to find the best idle. Went ahead and reset my base idle, reset my IAC and reset my TPS to .95 volts. Went for a small 2 mile ride and she is handling a little better. 1st gear is strong, 2nd still has some minor hesitation but it wasn't as bad as before. I'll go ahead and replace plugs tomorrow with motorcraft ones, currently running the NGKs and they are seeing some carbon build up. Any other suggestions. I really don't understand what happened with the hesitation and backfiring last week. I'll go for a longer ride tomorrow and let you know how it goes. By the way, not sure if this would matter but I have the 2.3L hooked up to a manual valve body with 3 gears. Is a blast but maybe the 2.3L being used to 5 gears so it's always going to have some sort of hesitation possibly?
 
#21 ·
"Is a blast but maybe the 2.3L being used to 5 gears so it's always going to have some sort of hesitation possibly?"


I've been building these for a long time and I can tell you that this is not the case, unless there's a mechanical issue.

So the vane air meter seems to be working? Were you also able to check the fuel pressure?

The symptom you're describing, sounds like a lean missfire, especially since it's happening under a load, not so much at part throttle or idle. Low fuel pressure can cause this.

I'll say this once more, spark timing has a direct effect on throttle response and generally speaking, you want to run as much spark lead as you can get away with. I really think you should try advancing your timing until you hear pinging under load, then back it down a degree or 2. Most turbo 2.3's can get away with 16-18 degrees of initial advance without pinging and in the process the'll pick up a bit of power and MPG in the process and also they will be far less likely to hesitate.
 
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#22 ·
Took her for another couple of mile ride today not really getting above 45mph, she is a bat outta hell in first, no issues at all with first gear and I was testing hills again. I can feel the turbo kick in and I can feel hesitation again coming up hills. Only really happens when I really put my pedal to the floor. She will start to pick up then just start hesitating. No backfire this time though, I just let off the throttle a little and all was good. I'll go ahead and check fuel pressure this week and let you know how that is. About the only thing I really can't do is timing, that's about the only thing I've never really done on a vehicle so I guess it's about time to learn. I'm thinking of replacing the fuel pressure regulater as well as I'm pretty sure it's the original on it, maybe that will help. So basically hesitation is still there but mainly when the turbo kicks in and I really put my foot on the pedal.
 
#23 ·
Did you do a boost leak test? The car will go flat with a boost leak once you hit enough boost to make the leak unable to hold enough pressure any longer. The VAM or MAF will read a given amount of air pre turbo. Then a boost leak will let some of that metered air escape and the A/F ratio will be pig rich causing the car to go flat or in some cases buck and sputter.
 
#26 ·
#1 Boost test, [Link in tech top of page how to make one out of pvc cap] Did this and found several on mine.
#2Fuel pressure test.38psi at idle with vac hose off regulator. [NO fuel in vac line if have that replace reg] A 5.0 adjustable reg will fit rail. Then put vac line back on and note pressure. Take for a ride with fuel pressure gauge on. Should be one psi increase of fuel pressure with each one psi on boost. If not check fuel filter, lines and fuel pump.
#3 Vam test. Test procedure in the link page also. Found this one recently haven't had to time to look at it much.
TheSamba.com :: Vanagon - View topic - Vanagon (Digifant) Air Flow Meter (AFM) Adjustment Procedure
Maybe change plugs to standard motorcraft plugs. Turbo motors don't like the split tip or multitip one's just some cheap motorcraft one. I personally have run 22psi on them. [Took out a motor too lean I learned]
Maurice
 
#27 ·
Thanks. Made a boost leak tester out of pvc cap, found a couple small leaks and fixed them. I'm noticing my idle rpm while in park is now higher so I am guessing that these leaks were acting as vacuum leaks and I'll need to reset my base idle and tps to get her to sit around 1000 rpm. VAM is good, replaced with a known working one. I am definately puttin motorcraft plugs in tonight and trying that. NgKs right now which I use on everything but I heard the same that the turbos are extremely figity with non stock. I need to test fuel pressure next, the regulater was not used on the rebuild. Still not as quick as I expected, does feel like it's sluggish until the turbo kicks in. I need to take it for a longer ride tomorrow to see if anything acts up
 
#28 ·
The EGR can leak boost. So may want to check there. I check mine by putting the tester on the output hose of the turbo. That way I could check intercooler and all. Keep psi under 10 for test I actually turned mine up higher in test and it blew off and almost hit me so that is a safety warning. Also the stem of the throttle plate leaks also. That little leak have to live with unless want to replace seal and or rebuild the shaft to throttle body. Mine leaks and runs ok.
Second mine is hooked up to a C-4 trans and motor is happy with it so makes no difference if not behind a 5 speed. Real advantage of auto no boost lost in shifting :grin: Maurice
 
#30 ·
Would you say it only runs poorly when the motor gets to operating temps or cold? How is it on cold starts? Does it start giving issues right away or after a few minutes? Did you change the TFI and did You put dielectric grease?
 
#31 ·
It's the same for both. It's good on cold starts. The issue is always there cold or hot, just seems like it's always trying to find its horse power. I'll push the pedal to the floor and it's just lagging and takes some time to gain horse power. TFI is a DynoMod
 
#33 ·
"It's the same for both. It's good on cold starts. The issue is always there cold or hot, just seems like it's always trying to find its horse power. I'll push the pedal to the floor and it's just lagging and takes some time to gain horse power. TFI is a DynoMod"

So, where you ever able to adjust the ignition timing, I recall you had some reservations about it. In case you haven't yet, I made a slide for you that will hopefully shed some light on it.

You don't necessarily need a timing light to make a timing adjustment, but it would be a good idea to at least make a mark on the distributor and the engine block to give yourself a point of reference. The distributor hold-down bolt is located at the base of the distributor. It's a little hard to reach, but you can fit a combination wrench on it if you try. It does not need to be removed, just loosened enough to turn the distributor. With the distributor bolt loose and the engine idling, you can rotate the distributor counterclockwise roughly half an inch. when you do this you'll probably notice the idle speed will increase. After you lock the distributor back down, go for a test drive and listen for pinging. The idea is to get as much timing as you can without pinging, which means that you will probably take several tries until you reach an optimal point. This empirical method is not the most scientific way, but it is very effective.







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#34 ·
Awesome thanks for the slide. I just replaced all plugs with motorcraft coppers hoping that makes it run smoother. Also installed a new O2 sensor as the old one was covered in carbon. Tomorrow after work I will test these out to see if any difference then I will start moving the dizzy if she's not running right. I have a fuel pressure tester on order but I really don't think it's fuel starvation but the holidays are around the corner so I will have a little more time in my days now to get her in tip top shape. I am hoping to have her trustworthy enough for longer distance rides right after Christmas. Will reply back tomorrow after I do the dizzy/timing you mentioned
 
#35 ·
How much pressure did you test to? What boost does the car run at? In case you didn't, you should always do a boost leak test at a few PSI higher than the boost level you actually run.
 
#38 ·
What are the new plugs gapped at? Is there anyways you can post a video of what's going on... It's easier to see and hear the symptoms. Maybe someone will notice something that happens when the surge happens, btw I don't remember if you said it or not but does it happen in low rpms or just driving in the 3k+ rpm
 
#42 ·
At 15psi, the test rig I made up. [same setup as the link] came loose and came flying by my head and missed my eyes by inches. If must test above that tie it down or something to prevent it coming out. The problem the cap has no ridge on it to prevent it from coming loose like the piping. That is my 2 cents worth. Maurice
 
#43 ·
Easy solution for that for the future. Find 4 stubby machine screws with round heads. Drill them into the cap, secure with a nut if you prefer, and then put silicone over them. Now you have 4 little nubs for your clamp to hold on to.
 
#44 ·
The test worked out pretty easily with the kit I made, ended up finding the boost leaks and fixing them. Changed plugs to motorcraft coppers and o2 sensor. I gapped plugs to .030 and still having the hesitation so I'll pull them and gap them too .034 tomorrow and try again. I need to go ahead and work on the timing as Ohc has posted as well because nothing seems to be working. I'll try the timing and the last thing I will be trying is the fuel pressure
When it arrives. I havnt had the sputtering backfire since the first post which is good but would still like to get rid of this hesitation. Seems to happen in 2nd and 3rd gear as I am trying to pick up speed. You can feel the car pull hard then start falling flat then start pulling hard again and then fall flat again. Hope I can get this solved. So far

Replaced VAM
Reset base idle
IAC has the restricter plate installed to rid of the surging idle
Cleaned IAC
Replaced plugs with motorcraft coppers gapped at .030
Checked for and fixed boost leaks
Replaced o2 sensor
 
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