Irregular Boost Issues
05-26-15, 12:14 AM
#1
Irregular Boost Issues
Hey guys,
I got an FD almost two years ago and had been driving it on and off since then. Since I was new to FD's I was unaware that I was running with significant boost issues. I recently installed a boost gauge to test my suspicions and found a very irregular boost pattern that I have been unable to find a writeup on. Hopefully one of you can assist.
At idle I have a solid 20 inHg's of vacuum. At low RPM, when I open the throttle to any degree I get zero boost until 2500-3500 RPM where I suddenly get a very solid and powerful 10 psi of boost. The point it comes on depends on speed, gear, and throttle position. I had always assumed this was the secondary turbo coming online, but all literature I can find mentions the secondary coming online around 4500 RPM. With WOT I get 10 psi that drop to around 5psi at ~5000 RPM and remains steady until redline.
Several other anomalies happen occasionally. For example, today when driving around 4000-5000 RPM, the car would surge though the boost gauge read a constant 10psi. Any idea where that could be coming from? Doesn't happen all the time, but very occasionally.
I originally thought that my secondary was performing well and was only lacking primary boost, but was unsure if this was the case. I plan on checking the CCV actuator tomorrow. I can hear the turbine spinning up so I don't think it is a bad turbine.
The car acted like this since I got it around two years ago. I made the mistake of buying the first FD I drove because it was at a decent price. The only mods I have installed are a downpipe and an aluminum AST which should not affect the boost pattern. The previous owner said no modifications were performed whatsoever, and seeing as he was an older wealthy gentleman that hardly drove the car I'm inclined to believe him. So what symptoms on a stock sequential system could cause this irregular boost pattern? Is it just the primary turbine giving me issues or do I have a bigger problem?
Thanks for your help,
Ryan
I got an FD almost two years ago and had been driving it on and off since then. Since I was new to FD's I was unaware that I was running with significant boost issues. I recently installed a boost gauge to test my suspicions and found a very irregular boost pattern that I have been unable to find a writeup on. Hopefully one of you can assist.
At idle I have a solid 20 inHg's of vacuum. At low RPM, when I open the throttle to any degree I get zero boost until 2500-3500 RPM where I suddenly get a very solid and powerful 10 psi of boost. The point it comes on depends on speed, gear, and throttle position. I had always assumed this was the secondary turbo coming online, but all literature I can find mentions the secondary coming online around 4500 RPM. With WOT I get 10 psi that drop to around 5psi at ~5000 RPM and remains steady until redline.
Several other anomalies happen occasionally. For example, today when driving around 4000-5000 RPM, the car would surge though the boost gauge read a constant 10psi. Any idea where that could be coming from? Doesn't happen all the time, but very occasionally.
I originally thought that my secondary was performing well and was only lacking primary boost, but was unsure if this was the case. I plan on checking the CCV actuator tomorrow. I can hear the turbine spinning up so I don't think it is a bad turbine.
The car acted like this since I got it around two years ago. I made the mistake of buying the first FD I drove because it was at a decent price. The only mods I have installed are a downpipe and an aluminum AST which should not affect the boost pattern. The previous owner said no modifications were performed whatsoever, and seeing as he was an older wealthy gentleman that hardly drove the car I'm inclined to believe him. So what symptoms on a stock sequential system could cause this irregular boost pattern? Is it just the primary turbine giving me issues or do I have a bigger problem?
Thanks for your help,
Ryan
05-26-15, 09:42 PM
#2
Upon further inspection today, I found more issues. The charge control actuator is actuating, but it is actuating in the wrong direction. When it actuates around 3500 rpm (hard to tell exactly when - had a friend on the throttle while watching it) it pulls the rod instead of pushing it out as the following troubleshooting guide says it should:
Troubleshooting
I also watched the precontrol actuator. It didn't do anything until it pulsed a little after coming off the throttle at high RPM's. My guess is a vacuum leak. That would explain how the charge control actuator doesn't have enough pressure/vacuum to pull closed until the turbo spools up at around 3500 RPM.
Any other thoughts?
Troubleshooting
I also watched the precontrol actuator. It didn't do anything until it pulsed a little after coming off the throttle at high RPM's. My guess is a vacuum leak. That would explain how the charge control actuator doesn't have enough pressure/vacuum to pull closed until the turbo spools up at around 3500 RPM.
Any other thoughts?
05-27-15, 12:23 AM
#4
Okay, I'm going to chime in since I had the same issue for a few days up until now. I actually just got home and am super happy with how my boost goes.
Any ways, it was a tedious process but I have the same setup as you (Stock car w/ DP)
After getting all my vac lines replaced and installing a boost gauge I noticed the same...
Primary turbo came in strong, the boost gauge would read a solid ~14PSI up until 4500rpm then it sharply dropped to 5psi all the way up.
The first time after the silicone hose job I tore in to it again and found that my Y-pipe coupler had a crack in it that was hard to seem replaced no luck, but better boost. Second time I disposed of the spring clamps on the 1" diameter hoses (ACV and CRV) still no luck
Re- checked my vacuum lines and re traced every thing, tested my vacuum canister and it was all good until I found one of my check valves was leaking.
Now I'm not 100% sure what did it but this last time I replaced the leaking valve with a good one, my vacuum chamber (top of engine) with a spare I had and re checked everything.
My car boosts now! I'm so happy with how it performs now. You should feel the car pull up to 4500 rpm then there's a "dead spot" that lasts a split second then it pulls hard up to redline.
Any ways, it was a tedious process but I have the same setup as you (Stock car w/ DP)
After getting all my vac lines replaced and installing a boost gauge I noticed the same...
Primary turbo came in strong, the boost gauge would read a solid ~14PSI up until 4500rpm then it sharply dropped to 5psi all the way up.
The first time after the silicone hose job I tore in to it again and found that my Y-pipe coupler had a crack in it that was hard to seem replaced no luck, but better boost. Second time I disposed of the spring clamps on the 1" diameter hoses (ACV and CRV) still no luck
Re- checked my vacuum lines and re traced every thing, tested my vacuum canister and it was all good until I found one of my check valves was leaking.
Now I'm not 100% sure what did it but this last time I replaced the leaking valve with a good one, my vacuum chamber (top of engine) with a spare I had and re checked everything.
My car boosts now! I'm so happy with how it performs now. You should feel the car pull up to 4500 rpm then there's a "dead spot" that lasts a split second then it pulls hard up to redline.
05-27-15, 01:45 PM
#5
I also believe I'm only on primary boost. I'm kinda happy about it because this is my first car with any sort of power so I'm glad I learned with less power rather than dealing with the primary and secondary all at once. The unpredictable nature of the primary boost is exciting though.
Thanks for the input rxmiles. I'm really thinking it is that/those check valve(s). Going to check them once the engine cools down.
Is there any downside to running the car in this condition other than the lack of power? Like I said the car has been like this since I bought it and I only just discovered the issue. I can't imagine it would be doing any damage to the internals because it's only running less boost than usual. Is this damaging any of the turbo system's components in any way?
Thanks for the input rxmiles. I'm really thinking it is that/those check valve(s). Going to check them once the engine cools down.
Is there any downside to running the car in this condition other than the lack of power? Like I said the car has been like this since I bought it and I only just discovered the issue. I can't imagine it would be doing any damage to the internals because it's only running less boost than usual. Is this damaging any of the turbo system's components in any way?
05-27-15, 04:25 PM
#6
So I tested a few things. First, the pressure chamber on top of the engine is holding pressure. It was released when I pulled one of the hoses off. Whether it's full pressure, I don't know.
Next, I tested the two check valves circled in orange in this picture: Imgur
Both valves work, but the connections on the right one were very loose and the valve itself was covered in oil indicating a leak. Hopeful, I put some zip-ties on the connections and took it out. Problem still persists. I can't tell if someone was different the first time I revved it up or if it was just wishful thinking. I'm gonna test all the connections I touched after dinner when it's done cooling down. Are there any other check valves I should be checking in particular, or is it time to pull out the vacuum chamber and check for leaks??
Next, I tested the two check valves circled in orange in this picture: Imgur
Both valves work, but the connections on the right one were very loose and the valve itself was covered in oil indicating a leak. Hopeful, I put some zip-ties on the connections and took it out. Problem still persists. I can't tell if someone was different the first time I revved it up or if it was just wishful thinking. I'm gonna test all the connections I touched after dinner when it's done cooling down. Are there any other check valves I should be checking in particular, or is it time to pull out the vacuum chamber and check for leaks??
05-28-15, 02:51 PM
#7
So I found what I thought would be the issue. In this picture I circled the check valve and connection in question:
It turns out the lower connection labeled 'G' had completely come off. But while trying to remove the check valve to assess the problem I snapped one of the plastic nipples. I did a fair job super-gluing it back together, but I'll still need to replace it. Wasn't too happy when that happened. I did reattach the connection at 'G' and tightened a zip-tie on it as best as I could but I'm still having the same issues. Next I will take out the vacuum chamber and examine if that is leaking at all, but that will have to wait until next week. I was really hoping that would do it. I'll examine the connections again once the engine cools off.
It turns out the lower connection labeled 'G' had completely come off. But while trying to remove the check valve to assess the problem I snapped one of the plastic nipples. I did a fair job super-gluing it back together, but I'll still need to replace it. Wasn't too happy when that happened. I did reattach the connection at 'G' and tightened a zip-tie on it as best as I could but I'm still having the same issues. Next I will take out the vacuum chamber and examine if that is leaking at all, but that will have to wait until next week. I was really hoping that would do it. I'll examine the connections again once the engine cools off.
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05-28-15, 10:06 PM
#9
Those nipples are super fragile, so be very careful, use a lighter if you can and heat up the vac line a bit, take it one step at a time. Trust me I was getting frustrated at the issue and it seemed to get worse before it got better. I spent all winter working on the car but it was mostly waiting on funds and parts. Once I had it all lined up it took a day to piece it all back together.
I don't know how mechanically skilled you are but seeing that you could reach your bottom solenoids let's me know you should be able to tackle the job no problem.
What I did
Completely removed the wiring harness and repaired or replaced broken wires or plugs. With the harness out of the way I removed the solenoid rack and injector rails and injectors which where sent to RC Engineering for service all new seals and filters.
Tested all of the solenoids out of the car, tested resistance at the coils and checked operation (closing/opening) and tested for leaks. I deleted the secondary throttle and by passed the coolant from the TB.
It's a tedious process but I am happy with my work, keep us posted and don't give up on the twins. I personally think they're gods gift t mankind but t each their own.
I don't know how mechanically skilled you are but seeing that you could reach your bottom solenoids let's me know you should be able to tackle the job no problem.
What I did
Completely removed the wiring harness and repaired or replaced broken wires or plugs. With the harness out of the way I removed the solenoid rack and injector rails and injectors which where sent to RC Engineering for service all new seals and filters.
Tested all of the solenoids out of the car, tested resistance at the coils and checked operation (closing/opening) and tested for leaks. I deleted the secondary throttle and by passed the coolant from the TB.
It's a tedious process but I am happy with my work, keep us posted and don't give up on the twins. I personally think they're gods gift t mankind but t each their own.
06-01-15, 03:40 PM
#10
Sorry for the delay. I was gone for the weekend. I won't need the car for the next few weeks so I plan on taking more of it apart than I was able to before. I'm not very mechanically skilled because I really don't have much experience. I was only able to reach the solenoid by having long/skinny hands and fingers as well as some patience. If I take it slow and find a guide or two I should be able to do whatever I need to. Knowing that, I would like to avoid taking off the intake manifold/TB if at all possible, though if it's required I will. You didn't find anything wrong with your solenoids, did you??
My next plan was to remove the alternator and vacuum chamber to check that. I can also check the pipes to the intercooler like Nakd n Fearless said, though I don't think that's the problem.
I don't have any plan on replacing the twins. I wanna see what they're actually like because this crazy setup is hardly controllable with the sudden boost and I doubt I'm making full power.
My next plan was to remove the alternator and vacuum chamber to check that. I can also check the pipes to the intercooler like Nakd n Fearless said, though I don't think that's the problem.
I don't have any plan on replacing the twins. I wanna see what they're actually like because this crazy setup is hardly controllable with the sudden boost and I doubt I'm making full power.
06-18-15, 04:43 PM
#11
Hey guys,
Sorry for the delay.
So I took off the vacuum chamber to pressure test and that was not the issue. Using the line connected to the vacuum chamber I pressurized the system and heard a leak from down inside the solenoid rack. To further investigate I took the TB and UIM off and it sounds like the leak is coming from the switching solenoid. I already ordered a replacement from Ray Crowe.
Figured since I was this far I'd also do a vacuum hose job so I just bought all the parts for that.
I feel a little in over my head mechanically but with the plethora of guides online and the fact that I've labeled absolutely everything I think I'll be able to work everything out.
Thanks for your help. I'll keep you guys posted how it turns out when I put everything back together.
Ryan
Sorry for the delay.
So I took off the vacuum chamber to pressure test and that was not the issue. Using the line connected to the vacuum chamber I pressurized the system and heard a leak from down inside the solenoid rack. To further investigate I took the TB and UIM off and it sounds like the leak is coming from the switching solenoid. I already ordered a replacement from Ray Crowe.
Figured since I was this far I'd also do a vacuum hose job so I just bought all the parts for that.
I feel a little in over my head mechanically but with the plethora of guides online and the fact that I've labeled absolutely everything I think I'll be able to work everything out.
Thanks for your help. I'll keep you guys posted how it turns out when I put everything back together.
Ryan
06-23-15, 09:07 PM
#12
Once I got the solenoid rack out I tested each solenoid and found the turbo control solenoid to be faulty. It was reading a low resistance and wouldn't switch reliably when powered. Replaced it with the new solenoid after checking it works and reassembled.
Now that it's all assembled I'm facing a whole slew of new issues. Firstly, the idle is pretty rough. When coming off throttle it dips low, recovers, and then oscillates just below 1k RPM while creating a good bit of smoke that I cannot identify the odor of. Once the engine warms up it creates less smoke but still an odor I cannot identify. The boost oscillates in harmony with the idle. When driving, the boost gauge says I'm getting nearly full boost, but after about 3k RPM power drops significantly and the car begins to lurch violently. When the secondary turbo comes online (and it does noticeably - yay) the lurching pauses and then becomes more violent. Does this have to do with more turbo control problems or is something more significant wrong?
Now that it's all assembled I'm facing a whole slew of new issues. Firstly, the idle is pretty rough. When coming off throttle it dips low, recovers, and then oscillates just below 1k RPM while creating a good bit of smoke that I cannot identify the odor of. Once the engine warms up it creates less smoke but still an odor I cannot identify. The boost oscillates in harmony with the idle. When driving, the boost gauge says I'm getting nearly full boost, but after about 3k RPM power drops significantly and the car begins to lurch violently. When the secondary turbo comes online (and it does noticeably - yay) the lurching pauses and then becomes more violent. Does this have to do with more turbo control problems or is something more significant wrong?
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