can a cutout cause a lean mixture

[crow]

I was having the engine tuned with the cutout open. The mixture read lean, too lean with a boost at 17.5. The conclusion was that having addding a big cold air intake, coupled with a 3.5 SS DP to a good 2.5 SS exhaust and running a TT 93 octane chip in a stock engine was too much.
Was able to lower the boost to 16.5 adjusting the timing. Looking at adding a Razor alky kit, as a cure. Any ideas?
PS, keeping my foot out of the boost as a precaution.

 

[SHADOWII]

Post...

more of your mods in your sig. it will make it easier to diagnose problems.
problem could result from a stopped up cat. convertor to a blocked air cleaner, fueling problem, to unmetered air, need more data.

 

[delcowizzid]

yes the cutout will make it run lean if the exhaust doesnt flow well .i just dropped off a full straight through 3" system and fitted a 3" dump for drag racing at 14psi it changed the fuel ratio from 10.4 to 11.8 lucky we had it setup rich before dumping the exhaust on purpose

 

[Nick Micale]

... Looking at adding a Razor alky kit, as a cure. Any ideas?.........

An alky kit will not solve the problem, get the A/F mixture right first.

If you are going to substitute alchy for gasoline in your mixture, it better be done by someone with the knowledge and experience, or it could result in replacing parts.

 

[Chuck Leeper]

Good flowing exh system.. [Ran 9's, over 141, thru exh]. Added a dump pipe, dyno'd the car. Dump closed vs open..3RWHP difference. FAST system datalogs showed little difference in afr.
Put a well designed dump on a good exh system, likely to see little imp...or...

Just like FOX News... We report, you decide!

 

[crow]

Shadow11, the cat has been deleted, air cleaner is new and huge. No fuel problems found, the fuel presure regulator seems to be working fine. Fuel pump is hotwired. Unmeterred air? How does the air get metered?

 

[crow]

delcowizzid, just droped in a new Pypes 2.5" SS exhaust with a 3.5" SS DP. We think that is the cause. Too much air through system?

 

[crow]

Nick Micale, get the A/F mixture right first? How to do that is the question. Tried adjusting but could not get the boost below 16.5. Fiends suggested the Alky kit, a Razor and replace injectors with new ones, possibly 60#s.
Have had the car most of its life without any problems. Now that I'm upgrading, the fun is starting. I know the quirks will get resolved but from now on I will do things in a proven way to avoid costly misteps. If that is posible
More input will be greatly appreciated. BTW, Not interested racing , jusxt a nice cruiser.
Crow the novice.

 

[aminga]

How close to the Cutout was the wideband sensor?

 

[crow]

aminga, I know nothing about the sensor hook up. I was outside the car watching on a desktop monitor and my friend was inside with a laptop. The ECM is just above the cutout or close?
I believe the ECM was connected to the laptop.
I'm thinking a new set of injectors will be a cure. An Alky kit is another cure. The Alky kit would be the better way to go for now. Later 60# injectors can be added.
The engine is strong but a thorough checkup is in order next. Timing chain, valve springs, small filter housing leak. My brakes are done and suspention is next. Better shops, improved spring rate and sway bars should do it.
Lots to do but one step at a time. Love the car.

 

[its2qik]

Nick Micale, get the A/F mixture right first? How to do that is the question. Tried adjusting but could not get the boost below 16.5. Fiends suggested the Alky kit, a Razor and replace injectors with new ones, possibly 60#s.
Have had the car most of its life without any problems. Now that I'm upgrading, the fun is starting. I know the quirks will get resolved but from now on I will do things in a proven way to avoid costly misteps. If that is posible
More input will be greatly appreciated. BTW, Not interested racing , jusxt a nice cruiser.
Crow the novice.

I DO NOT recommend fixing the problem by adding alky. That is a recipe for disaster, IMO. Bigger injectors (60s would work) and a good fuel pump ought to fix what's ailin' ya.

 

[Black Power]

How close to the Cutout was the wideband sensor?

That's what I was gonna say. When I open my cutout it shows really lean on the WBO2 sensor, when it's capped off it's where it should be. If your sensor is down by the cutout that's going to cause it to read funny when you are not under boost.

 

[chopped39]

aminga, I know nothing about the sensor hook up. I was outside the car watching on a desktop monitor and my friend was inside with a laptop. The ECM is just above the cutout or close?
I believe the ECM was connected to the laptop.
I'm thinking a new set of injectors will be a cure. An Alky kit is another cure. The Alky kit would be the better way to go for now. Later 60# injectors can be added.
The engine is strong but a thorough checkup is in order next. Timing chain, valve springs, small filter housing leak. My brakes are done and suspention is next. Better shops, improved spring rate and sway bars should do it.
Lots to do but one step at a time. Love the car.

Do you have wideband 02? Or were they using a stand alone gas bench?
Post all the data that you have. I have seen people tring to tune with a gas bench and dyno. Those numbers are skewed bigtime because your only getting a little sample. Post all your mods

 

[Chuck Leeper]

Adjusting the timing to control boost?
Won't go below 16?? Is the w/g hole matched to the puck?
Is the w/g diaphram a HD unit?
How is the w/g controlled?
What is the duty cycle on the injs? [If reasonable, bigger injs are not the cure]
Fuel psi is? Does it rise w/ boost?
Exhaust system leaks pre O2 sensor?

 

[crow]

Chuck Leeper, timing adj. 2* and it helped boost but not enough.
Correct, boost wont go below 16 at higher RPMs.
Not sure if the puck and wastegate hole are matched. Installed a 3.5 DP on a stock turbo. Was told it would work. Cant believe it would be otherwise. Looked at the matchup closely.
The w/g is internal and the actuator was stock. The actuator was changed to an adjustable.
Cant say about the duty cycle but the engine runs smooth, responsive and powerful. No smoke coming out of exhaust.
Mechanic tells me it would not hurt to change the inj. but they are fine. I will change them eventually but for now solving the problem is the priority.
Fuel psi rises with the RPMs and boost.
No exhaust leak noted. Everything tight.

 

[motorhead]

How lean is too lean? And where in the powerband? We are assuming it is WOT because you are talking about peak boost.

I was outside the car watching on a desktop monitor and my friend was inside with a laptop.

He was in there with a laptop doing WHAT exactly? Playing solitaire?

This is why I ask:

TT 93 octane chip

Because if you have one of Eric's TurboTweak chips you (or your laptop wielding buddy) can effectively increase the fuel to adjust for WOT conditions (among other things). Was this performed? Do you own or have access to a scantool? If not go and buy a Powerlogger and get really familiar with it.

I don't trust many friends with my Buick, even friends who have owned one. You'd better become damn intimate with yours if you want to have a positive relationship with it. There is a reason our wives get jealous.

 

[BIGPSI]

you need to learn how to tune that thing and understand all of the readings! you shouldn't have put a 3.5" downpipe on a bone stock car,without other proper mods,like new fuel pump hotwired and injectors.

 

[crow]

BIGPSI...pump is hotwired. Thanks for the advice.

 

[crow]

MR.T, at 4,382 rpm we got 16.9 boost, 64.8 fp, a/f 14.1. That is where we stopped. The boost kept creeping higher.
As to learning, that is why I'm here. The journey starts with the first step. As to my friends? Very knowlegable, I have confidence in them. However, no one knows everything. Been looking for a scan tool. I have budget constraints. Getting the car running right is first, the keeping it that way is next.
Putting a 3.5 DP on the stock motor may have not been wise but it was not ALL THAT bad. After all, the car has dual 2.5 exhaust. That amounts to 5". Perhaps the intake is more at fault. 4" filter and pipe to a stock MAF then 3" to the stock turbo. That is a far cry from the original air intake system, don't you think? More than likely it is the combination of both that is doing me in. Now I'm hooked, hhh! Got to go forward with it till it is really safe to drive, first priority.
Keep in mind guys, I'm ignorant. I knew I would not get the full benefits of these mods but I did not dream they would have an adverce effect on the motor. My old muffler system had holes in it and needed replacement. Why not upgrade?
Thanks for the help.

 

[crow]

Chopped39, we had a wideband. I have 6 pages of printout. More info than I care to post but here is where we stopped:
EngSpd......4,382 rpm
CWhlPw.....248.3 CHp
EngPwr......296.5 Ehp
STPTrq......320.0 Clb-ft
Speed.........87.9 mph
OilTemp.......77.8 deg F
LamA/F.......14.1 ratio
BoostP........16.9
FuelP..........61.8