New DSM owner, fuel cut question

[Quattro18t]

Hey all my name is Joe. I own a 99.5 audi a4 1.8t quattro 5 speed for my weekend driver/ mod car. I just bought a 1991 Talon TSI AWD with 30K on rebuild motor, and 25K on transmission. It has the following mods: spec stage 3 clutch
buschur racing ported axhaust manifold
HKS 50mm external wastegate
2.5 inch slowmo o2 housing
3 in mandrel bent exhaust w/cutout
2 in megan racing lowering springs
kyb GR-2 struts up front
kyb AGX struts in the rear
factory wheels painted gunmetal

It is my daily driver for now and I have a question about fuel cut I am experiencing. Whenever I gun it, boost will kick in around 3500-4k rpms and spikes up to 15psi sometimes (wastegate creeps past stock boost), around 5500rpms I will hit fuel cut and the car will surge until I let off the gas. I know the wastegate is too large for the stock turbo but is there any spring I can purchase for it to make it not spike such high boost or would I be better off going back to a stock wastegate?

 

[bowtiebuba350]

your car is seeing to much airflow you need somethin to tune with like a safc but befor you do that you need to get bigger injectors like 550s a fuel pressure regulator and a fuel pump to beable to tune safely

 

[Quattro18t]

I know it has a fuel pressure regulator on it, I'm not looking to throw tons of money into the car. I would ###### be better off with a stock wastegate?

 

[p1s70np0w3r]

You have to get some sort of tunning, dsmlink, safc, eprom ecu with a eprom chip made...

You need to tune the boost down or you will damage the motor from fuel cut.

A fpr is nothing, it only controls fuel pressure not your injectors or fuel pump which might be maxed out.

 

[iluvmy4g63]

there are springs that you can buy for the wastegate but i don't understand why its doing that. i ran mine with 16psi when the only mod was a boost controler(16 is about max with out other mods).there manydifferant ways to get rid of it. but i would check the timing. because knock can be caused buy that.( to lean).

 

[p1s70np0w3r]

What turbo are you running on that thing?

 

[Quattro18t]

turbo is stock. Can I just buy an SAFC and tune it for lower boost?

 

[iluvmy4g63]

no. the min amount of boost is controled buy the spring in the gate. also is the flapper welded shut? if so you can not put stock internal gate back on.

 

[p1s70np0w3r]

turbo is stock. Can I just buy an SAFC and tune it for lower boost?

Are you sure of that pics?

 

[Quattro18t]

I'll get some tomorrow when I get a chance.

 

[p1s70np0w3r]

TDO5H is stock but i need pics to tell if it is a 14b evo 16g or big/small 16g

 

[Diplomat]

Let me save you guys some time here.

Here's one of my old fuel cut replies, along with 79 pages of posts on the subject... what it is, how to fix it.

Don't forget to check for boost leaks too. They contribute to fuel cut.

Off topic here... Quattro, I don't understand. Why aren't you using the newer Audi as a daily driver instead of a 17 year old modified DSM? I'm not knockin' your decision to do so, I'm just curious. Seems like it would be a lot cheaper to mod and race the DSM, and use the Audi to get to work.

Edit: Oh, since you have a '91, it would be a good idea to check and see if you have an EPROM ECU or not (there's a chance, but no guarantee). I know you said you weren't looking to spend a lot, but when it comes to tuning, most DSMers are all about DSMlink due to it's relative ease of use and "tunability", if you will. But first you need a socketed EPROM.

 

[Quattro18t]

Let me save you guys some time here.

Here's one of my old fuel cut replies, along with 79 pages of posts on the subject... what it is, how to fix it.

Don't forget to check for boost leaks too. They contribute to fuel cut.

Off topic here... Quattro, I don't understand. Why aren't you using the newer Audi as a daily driver instead of a 17 year old modified DSM? I'm not knockin' your decision to do so, I'm just curious. Seems like it would be a lot cheaper to mod and race the DSM, and use the Audi to get to work.

Edit: Oh, since you have a '91, it would be a good idea to check and see if you have an EPROM ECU or not (there's a chance, but no guarantee). I know you said you weren't looking to spend a lot, but when it comes to tuning, most DSMers are all about DSMlink due to it's relative ease of use and "tunability", if you will. But first you need a socketed EPROM.

Thanks for the info. The reason I am modding my audi is because I like to be different. Yes, its more expensive but I'd love to smoke someone in a 4 door Audi that no one has any idea its fast.

 

[JayRolla]

Finally diplomat gave some good info. All these guys saying tune, get fuel mods wont do anything to stop your fuel cut.

The guy that said you will kill your motor from fuel cut is also wrong because its a safety feature to save the motor when it sees to much air flow.

I would turn down the boost but I bet that wastegate wont let you. If you are running an external off the manifold or o2 housing most likely the internal gate on the turbo has been welded shut and you need to use the external gate.

I would get the right supporting mods so you can run that 14b at 15-20psi. I would also check for boost leaks and make sure thats not causing the fuel cut. Look into getting a maf-t since the stock maf is limited.

 

[theebluecrx]

Have you hacked your mass yet?

 

[90laserRSfwd]

I think all you wanted to know was how to get the boost down a little lower correct ? Can you get us a pic of the turbo and wastegate, also when you take a pic of the turbo, pull the intake hose off and get a good clear shot of the compressor wheel....

 

[Quattro18t]

I got some quick shots, didn't have time to pull the hose off the turbo inlet but I'm almost 100% sure its a 14b turbo.

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[Re4peR26]

Not to knock on you or no offence from this but. I have a 2004 Jetta 1.8t that i have over 3k in to and im still only running 14.2's alot of EIP packages installed on the vehicle on EIP tuned it. Turned in to a very unrelable.. and still Slow jetta. I would just Use the audi for daily driving. I have about 900 bucks in my dsm and its faster then my jetta... Just my 2cents...

 

[Quattro18t]

Well, I prefer to mod the audi because I have a decent amount of mods in it and just fell in love with german cars. I have a T3/T4 setup about to go on and I'm expecting about 330awhp/350awtq with full supporting mods and a tune.

 

[Diplomat]

Is there a big crack in the wastegate plumbing? Or is that a shadow from something?

 

[kenamond]

I'm not a 1g guy, and those who are and *know* the answer feel free to correct me if I'm wrong, but...I don't think you should be hitting fuel cut at 15psi. I'd highly recommend that you do a boost leak test if you haven't already and fix any leaks. I didn't read the "fuel cut" thread mentioned above (sounded kinda long ), but that's one common reason for it. These DSMs are quite finicky about boost leaks.

 

[DontStartModdin]

I'm not a 1g guy, and those who are and *know* the answer feel free to correct me if I'm wrong, but...I don't think you should be hitting fuel cut at 15psi. I'd highly recommend that you do a boost leak test if you haven't already and fix any leaks. I didn't read the "fuel cut" thread mentioned above (sounded kinda long ), but that's one common reason for it. These DSMs are quite finicky about boost leaks.

Well he is in Ohio, so it is pretty cold there right now. So, it's definitly possible to be hitting fuel cut.

Is there a big crack in the wastegate plumbing?

I think your right. That's not good.

 

[JayRolla]

I'm not a 1g guy, and those who are and *know* the answer feel free to correct me if I'm wrong, but...I don't think you should be hitting fuel cut at 15psi. I'd highly recommend that you do a boost leak test if you haven't already and fix any leaks. I didn't read the "fuel cut" thread mentioned above (sounded kinda long ), but that's one common reason for it. These DSMs are quite finicky about boost leaks.

With the stock 1g maf and being very cold out he could be hitting fuel cut but I'm guessing its from a boost leak also. I'm running a 2g maf and at 9psi I still hit fuel cut. Boost holds pretty good but I do have some leaks at the TB.

Me and my mechanic cant figure it out and I'm about to through in a maf-t just to get rid of the issue. Its wierd because my bro's car is running 25psi on a 2g maf with no issue and he has the same little leaks I do at the TB.

 

[JusMX141]

Boost leak for sure....check the upper neck of the stock intercooler (under the hose connection) for pinholes.

No offense, but the underhood of that car is quite hacked up....particularly the straight piece of Walker exhaust piping for your upper intercooler pipe. What I mean by this is that there could be boost leaks anywhere.

I'm also wondering why such an ENORMOUS wastegate to control a relatively low boost level on a 405cfm turbo?

 

[Lonnie gandee]

You said you bought the car like this? I bet its always had this problem.

You need to pull the turbo off and remove the flapper door completely, instead of having it just dangle around, or tacked open, or however it is.....

That will solve the creep issue. You can have a giant external on a small turbo, but with the path restricted by the flapper, there's not enough air relieve.

And that looks like the 4omm std gate.