1G Hitting a brick wall in 3rd gear

[Vincent Pandolph]

1990 tai AWD, walbro 255, -6 fuel lines feed and return, jmfabrication fuel cell, fuel lab afpr, cooper core plugs at factory gap ( I didn't check them), new wires, ptu and coil, 3" down pipe, 3" test pipe, 2.5" cat back, Grimspeed V2 MBC, 93 octane. I'm having same kinda issue, I just started to add boost, got to 15 psi. At prolonged wot in 3rd gear around 6k rpm noticed power drop accompanied by a loud pop. I thought I blew a coupler. Pulled over all good, no boost leaks, I have a tester. This sounds like plug gap? Or it needs to be tuned?

 

[Mech Addict]

Is it simply that the wastegate is opening? I mean that is a sort of boost leak, though obviously not on the intake side. When you say hit a brick wall, like you actually begin dropping rpm, or it just quits climbing? Knock sensor among a few other causes will do this to preserve the motor. Run some octane boost and see if that helps. Easy test, anyway.

 

[Vincent Pandolph]

More of a bucking, but not repetitive, and also loud pop like a coupler came off.
I checked and all is well. I'm going to tighten up the gap on the plugs and go again. Probably tomorrow though car is pretty hot and I don't have my tools right now.

If anyone else has a suggestion in open to hear it. My son says it's because of the larger exhaust and increased boost pressure, it's not tuned. However I had a 91 TSI AWD and everything was stock, ran 18 psi no problems... maybe my kids right?!

Also afr's in the mid 10's when this happened. Does it every time I hit 15psi and hold it.

 

[Tyeler18]

Inconsistent bucking sounds like spark blow out. If you didn't check plug gap then they're probably gapped at the .04X gap that n/a 2.0's call for as is all the "pre gapped" plugs for these. Gap them down to .028 and do a boost leak test.

 

[Vincent Pandolph]

Thanks Tyeler18, I have tested for leaks as I have just had the intercooler outlet pipe replaced. I have a 2" h ac elbow with a PVC cap clamped on one end with a schaeder valve so I can put air into the system, and plug for bov tube. Pinched the other 2 smaller hoses off. No leaking that I could tell, although I did not have a gauge to time reference.

Also afr's are 10.5 at wot 15 psi. I'm leaning towards the plug gap, because I didn't check upon install, also you mentioned that the plugs come gapped for use in n/a engine. Will have to check tomorrow though, getting dark out and I need a new gapper. Update to follow

Other than the pre gap of non turbo plugs being different can they still be used if gapped correct? I had detonation occur while at 15psi of boost, right around 6200 RPMs. Power dropped like car was dead and loud solitary pop like I busted a coupler. Can that be from wrong plug gap? All timing settings are stock, engine not modified. Only upgrades are afpr, -6 fuel lines, walbro 255, big exhaust, and Grimspeed V2 MBC.

 

[pauleyman]

Thanks Tyeler18, I have tested for leaks as I have just had the intercooler outlet pipe replaced. I have a 2" h ac elbow with a PVC cap clamped on one end , with a schaeder valve so I can put air into the system, and plug for bov tube. Pinched the other 2 smaller hoses off. No leaking that I could tell, although I did not have a gauge to time reference. Also afr's are 10.5 at wot 15 psi. I'm leaning towards the plug gap, because I didn't check upon install, also you mentioned that the plugs come gapped for use in n/a engine. Will have to check tomorrow though, getting dark out and I need a new gapper. Update to follow

I see the original post is 10 years old, similar post but its probably better to start your own thread for these situations. Moving on...
Brick wall pop but everything is fine...sounds like fuel cut. Spark plugs do NOT come gapped for NA. They do if you buy the NA plug but a turbo plug will be close. NGK stock is BPR6ES or BPR6ES-11 (NT) respectively. For a 1g anyway.

And just like the OP please post a profile. Easy to keep up with it there.

We can help you diagnose but it's tedious when you post similar problems in multiple posts.
What plug did you install that you think it's an NT plug? If you use it the electrode will be bent over the center. It's not optimal but the car will physically run. Under load? Who knows.
Everything you've described sounds like fuel cut (which can change depending on ambient temp). Until you know for sure what plug and gap you have it's not worth diagnosing. Find out for sure and get back with us. Do you have a non stock boost gauge so you know fur sure what you're doing?

 

[Vincent Pandolph]

Pauly, yes I have a boost gauge, and AEM WB. I have ECMLink v3, but it isn't in yet because I don't know what to do once I plug it in to the car.

I have some working knowledge of the car as I had a 91 TSI AWD 20 years ago and ran 18 psi with no tune and everything stock including the exhaust. I know all cars are different in little ways, and will have subtle difference between them.

I'm walking to the parts store tomorrow morning so I don't have to wait for the engine to cool. I'm getting new plugs, ngk copper core, and a plug gap tool. Btw it has ngk copper in it currently, but I didn't check the gaps. Before I installed the MBC it was running 9psi and rich in the 9's wot. I had a squeaky belt issue due to the wrong power steering belt. Fixed that and AFR was in the 10's. Noticed that my volt gauge was also reading .8 volts higher and engine was running smoothly.

 

[pauleyman]

Pauly, yes I have a boost gauge, and aem wb, I have ECM link v3,but it isn't in yet because I don't know what to do once I plug it in to the car.

Install it. Nothing you need to do and you get data logging atva minimum. That alone is worth firging ahead. Ecmtuning.com

I have some working knowledge of the car as I had a 91 TSI AWD 20 years ago and ran 18 psi with no tune and everything stock including the exhaust. I know all cars are different in little ways, and will have subtle difference between them. I'm walking to the parts store tomorrow morning so I don't have to wait for the engine to cool. I'm getting new plugs, ngk copper core, and a plug gap tool.

Do yourself a favor and skip all the "gap tools" and just get feeler gauges.

Btw it has ngk copper in it currently, but I didn't check the gaps.

What model plug? Pull one and see. Yiu may already have the right plugs. Stock is bpr6es AKA 7131

Before I installed the MBC it was running 9psi and rich in the 9's wot. I had a squeaky belt issue due to the wrong power steering belt. Fixed that and afr was in the 10's. Noticed that my volt gauge was also reading .8 volts higher and engine was running smoothly.

 

[Vincent Pandolph]

So my fuel pressure is set to 34 psi engine warm and running. My afr was at 10.4 at 6000 rpm and hit fuel cut???

Would raising pressure to 37 fix it?

Or look somewhere else, fuel cut caused by ECU seeing more air than it's programmed to see?? Doesn't make sense as I know from experience that a 1g can run 18 psi completely stock and will hi it boost cut first due to BOV restrictions.

I do have a CEL for injector circuit. Fuel system got rusty because of bad gas tank. Replaced with jmfabrication fuel cell and blew old fuel out of system with compressed air, replaced Weldon racing filter, and filter in tank. I know fuel system is clean, but perhaps an injector or 2 is a bit dirty. Causing the fuel cut because it knows it can't keep up with the fuel demand? Whatever going to check plugs and /or replace them and make sure gap is good. If that don't work I will put the 850cc injectors in and install ECM link.

 

[steve]

Please stop reviving old threads. It's great that your searching but just stick with putting your questions in a thread about your car since people are already watching it.

Regardless to what you think you know, fuel cut is caused by the ECU turning off the injectors when it thinks too much air is running through the engine. It's programmed to keep the engine from self-destructing if the wastegate or it's pressure hose fails. This code is in the stock ECU and is one of the things DSMLink will remove.

If you think you are hitting fuel cut early, you should locate and resolve all boost leaks, that will drop the air counts and reduce the load on the turbo compressing air that never reaches the cylinders.

When you're measuring the base fuel pressure are you doing so with the pressure reference hose disconnected and plugged? What is your vacuum reading at idle. The fuel pressure at idle with the hose connected should be equal to the base fuel pressure minus the engine vacuum (converted to psi), so a 1G manual turbo is somewhere around 27 psi at idle with the hose on.

If you have an active injector CEL you shouldn't be running it to WOT.

 

[pauleyman]

So my fuel pressure is set to 34 psi engine warm and running. My afr was at 10.4 at 6000 rpm and hit fuel cut???

Would raising pressure to 37 fix it?

Or look somewhere else, fuel cut caused by ECU seeing more air than it's programmed to see?? Doesn't make sense as I know from experience that a 1g can run 18 psi completely stock and will hi it boost cut first due to BOV restrictions.

I do have a CEL for injector circuit. Fuel system got rusty because of bad gas tank. Replaced with jmfabrication fuel cell and blew old fuel out of system with compressed air, replaced Weldon racing filter, and filter in tank. I know fuel system is clean, but perhaps an injector or 2 is a bit dirty. Causing the fuel cut because it knows it can't keep up with the fuel demand? Whatever going to check plugs and /or replace them and make sure gap is good. If that don't work I will put the 850cc injectors in and install ECM link.

Steve already pointed out what I wanted to say but I'm going to reinforce this. Stop reviving old threads, fill out a profile (many requests to do so) and again fuel cut is NOT based on fuel flow. It's based on airflow. You can install giant fuel pumps and big injectors and it doesn't matter. It's in the code of the ecu based on airflow. Go after the problems you know about and make sure those are fixed THEN start diagnosing. Anything else and you're pissing in the wind.

 

[Chumpaumpalumpa]

Put Link in the car. You're hitting boost cut

 

[Vincent Pandolph]

Soad, you're saying that I'm putting too much air into the engine based on what the ECU knows it can support? Based on what the fuel system was designed for? Shock racer, it's stock 1g recirculating.

I thought I solved issue by changing to BPR7ES, but it didn't solve the issue. I'm going to check again for air leaks, but this time I'm adding a gauge to check for pressure drop that would indicate a leak somewhere. Also I have a code for injector circuit code #41.

These two different problems may be related. Going to swap in my 850 cc FIC injectors and install ECMLink. I should be able to solve everything that's wrong.

 

[pauleyman]

Please please stop posting in old threads. Fuel cut has NOTHING to do with the fuel system. If your symptoms went away with new plugs, even temporarily you need to reasses.
Make a new post and post the problem and all relevant info.
And again please post a profile.
And read this

https://www.dsmtuners.com/threads/diagnosis-101-ask-good-questions-to-get-good-answers.540259/

 

[pauleyman]

You must solve the codes. I would advise do not go ANY further until you solve what the computer is telling you. You're chasing a ghost and the direction is clear. Fix that code first then see what happens.

 

[trogador2005]

Try leaning out to 11 or 11.2. most of the 1gs I tune, hate anything richer than 10.9-11