Something isn't right w/ my engine

[DefEddie]

I would suggest starting most of your tuning over.
You've been tuning a symptom up till now,and you don't know how flow was affected at all off-idle situations.
I would almost erase everything and go right back to the stock file and start over.

[Schmieder]

You keep saying you have Tuned the VE tables (most VE is pointless but not in all cases)
But have not mentioned much about PE?

If you are going lean under load, are you in PE Mode? have you tuned for PE?

No, PE is disabled until I get the fuel pressures under control. That would be a disaster. There is no way I can tune PE yet.

And in fact, I add to the VE tables to balance the trims and the PCM is yet asking for more. I add more, it asks for more yet still. It is apparent the PCM can't get what it is asking for. At first, the tables were tuned but the pump is dying fast. It sounds like there is loose bolts and gravel in it now. Such a terrible grinding sound.

So in a way, the VE tables aren't tuned anymore. Due to the lack of fuel pressure the VE tables will never be tuned right. So I need to start from stock again once the new pump is in.

This is a lesson for those who think about tuning. Keep your stock file!!! I did and I am glad I did. In fact, I kept a copy of each change I flashed.

[Schmieder]

I would suggest starting most of your tuning over.
You've been tuning a symptom up till now,and you don't know how flow was affected at all off-idle situations.
I would almost erase everything and go right back to the stock file and start over.

Exactly what I am going to do as I posted one up. Since the fuel delivery has been distorted from a lack of pressures, everything I did was built on false data.

[DefEddie]

Awesome,if you need any base files for anything i've got several still around here from developing the TC v6 calibration base i'm pretty sure.
No 35/3900 stuff I don't think though.

[Schmieder]

Awesome,if you need any base files for anything i've got several still around here from developing the TC v6 calibration base i'm pretty sure.
No 35/3900 stuff I don't think though.

TC v6 as in turbo? Yeah, I'll check em out. They may be a great reference/study aid so I can compare differences and investigate the why, how, ect. But only if it isn't a problem uploading them as it isn't critical. I have my stock files and several guides to tuning. Plus I seem to have a handle on the art of tuning. At least the easy, medium level stuff. Too bad my first run at it was corrupted data. I tell ya, as soon as I saw the PCM command more fuel after adjusting VE in SD mode w/o and misfires and knowing the fuel rail lost nearly all pressure after shutdown, it was obvious. New injectors, new FPR, no line leaks....it was the pump check valve and the pump sounds so freaking terrible.

Should be Hmmmmmmmmmmmmmmmmmmmmmmmm...click
Now its Grrrrr eeh grr eh eh thud ..thud .....thud .......thud ..................thud..clunk


I decided to get a 2-bar MAP just in case the MAF fails for some reason. Lord knows it does happen and I don't want it to happen under boost or my engine may be toasted.

So I see the 1990 Pontiac Sunbird Turbo 2.0 has a 2-bar MAP. I can get one for $54.00 from GMpartsdirect.com new. It should fit fine even if it needs slight modding for fit. Unless anyone can suggest otherwise or a better 2-bar.

[robertisaar]

Syclone/Typhoon also used a 2-BAR MAP...

[IsaacHayes]

I'm trying to figure out tuning the VE tables with 2 bar... How they would look etc. They would look a lot lower everywhere under 1bar if I'm thinking right, but I'm also working ATM so not putting a lot of thought towards it.. LOL

There are 2 bars everywhere... Look in the For sale section here...

[Weatheralls Auto]

I have a few 2 bar maps for my project, but the turbo wont be till next year so could sell one if ya need it. No modifying, direct replacement.

[robertisaar]

honestly, this seems like a ghetto way of going about it, but sometimes there are no alternatives....

let's consider that a 1-bar MAP will report ~2.2 volts at 50kPa. a 2-bar will report roughly half of that at the same amount of vacuum.

so: let's assume a VE of 50% at 2000RPM and 50kPa. with a 1-bar, we'll see 2.2volts from the MAP. let's also say that the engine is ingesting 50grams/second of air at this point. since a 2-bar would report ~half the voltage(and therefore, ~half the actual kPa), the engine would think it's at 2000RPM and 25kPa. so the actual value from the 2000/50 cell would need to be in the 2000/25 cell. intuition says that unless some funky reversion is happening, the 50kPa VE would be higher than the 25kPa VE, so i would expect to see higher numbers in the VE cells.

IMO anyway.

[DefEddie]

I meant TC as in Tunercats,I gathered a bunch of different calibrations from some different GM v6 platforms to develop the v6 file base for tunercats OBDII/JET dynamic spectrum tuner.
I was just one of a bunch of people,but I am pretty sure I still have the folder around here somewhere on a computer. All are base files,not modified.

For a MAP sensor I plan to try out Autometer's part number 2249 (30 PSI MAP sensor 3 bar).
The plug and body look identical to the GM unit,and they also carry a 15 psi unit(2bar) part number 2247.
Something to check into,it's about $70-$80 IIRC through autozone.


*found this also,all 3 bar maps though.

GM Style 3 Bar Pressure Sensors

Manufacturer Part Number
GM (old)* 16040749
AC Delco (old)* 213-101
GM (new)** 12223861
AC Delco (new)** 213-1562
Borg Warner** EC1678
NAPA CRB219481
Holley 538-23

[Schmieder]

I meant TC as in Tunercats,I gathered a bunch of different calibrations from some different GM v6 platforms to develop the v6 file base for tunercats OBDII/JET dynamic spectrum tuner.
I was just one of a bunch of people,but I am pretty sure I still have the folder around here somewhere on a computer. All are base files,not modified.

For a MAP sensor I plan to try out Autometer's part number 2249 (30 PSI MAP sensor 3 bar).
The plug and body look identical to the GM unit,and they also carry a 15 psi unit(2bar) part number 2247.
Something to check into,it's about $70-$80 IIRC through autozone.


*found this also,all 3 bar maps though.

GM Style 3 Bar Pressure Sensors

Manufacturer Part Number
GM (old)* 16040749
AC Delco (old)* 213-101
GM (new)** 12223861
AC Delco (new)** 213-1562
Borg Warner** EC1678
NAPA CRB219481
Holley 538-23

IIRC, as long as it is designed for GM and can read 1bar positive pressure it will be satisfactory. Though, 3bar would be nice for the future when I plan to rebuild the block with forged pistons, ect.

The MAP for the 1990 Sunbird 2.0 Turbo should work fine as the voltage readings are about the same due to the mechanical properties of the sensor itself. I can get that MAP for $50. Minor modification to fit is no big deal. I just need to scale the tables in HPT which won't be hard at all. I consider myself quite well in math and problem solving. In high school, I was the only 11th grader in advanced calculus/triginometry. But I hated english so excuse my spelling.

Now I have a question about dropping the fuel tank. Yesterday when building a stronger more professional support for my exhaust system, I noticed I had better access to the fuel tank when the front of the vehicle was jacked up on stands. I feel I can remove the tank properly with the clearance I have that way.

Questions I have are this....

How likely is it for the straps to snap since they are 12 years old?

Moderately rusted but I can still see steel. The tank was replaced 3 years ago due to a crack so the bolts should be fine to remove with out snapping.

As the procedure appears, I disconnect the filler neck at the cap, support the rear side of the tank to pivot on. Place a jack with 2x4 under front of tank to gently lower once straps are unbolted.

Now, can I remove the fuel pump with the tank's front side lowered or must I remove the tank entirely? The pump is smaller then I would have imagined so it seems possible. Just want professional advice on tank removal and any thing I should be aware of to prevent breaking anything.

I can disconnect the 3 lines running to the tank easily enough and label them for error free connects.

How about the power connectors? Are they disconnected from underneath before the tank is lowered or do I have to lower it some to reach them as I can't see them yet. Or are they the wires that are running through the trunk to the under body near the rear seat?

After reading install instructions, the pump swap seems very easy and straight forward. It is the tank removal that concerns me.

Any advice or precautions regarding would be very well appreciated.

Oh and base tunes, its ok, I don't need them. I have access to many 3100/3400 base files from HPT's repository. Even some turboed 3800 files (usless for me but I can check them out for differences).

[DefEddie]

I read your other thread so I know you already got the new pump in but heres some answers in case others wondered.

Most of the time the straps and tank will be rusty,this is never a problem though.
Badly rusted bolts can snap and break,other than that they aren't an issue really.
On even the worse ones i've had some lube spray and my impact spin them right off.
I've never seen bands rusted so far as to need replacing,even on the most corroded,salted northern vehicles that have come through our shop (we're in the south.)

The inside of the tank is where you want to inspect for rust,disregard the outside for the most part. If it's inside then you got issues and need recoated or new tank.

Best way to do it is to drain the tank first.
Most vehicles have flapper valves/anti-siphon valves and siphoning is redneck anyway.
The high tek rednek will disconnect the fuel pump outlet side line and run a hose from the fuel filter to gas jug.
Then you pull the fuel pump relay and install a jumper across the appropriate pins power the pump manually.
After the fuel is out support the fuel tank,on the ground you'll use a big jack.
Jack it up till it just touches the tank,no pressure needed.
Unbolt the fuel fill hose if you can reach it,along with the fuel fill breather line.
If you can reach any of the other lines,disconnect them.
Unbolt the strap's and remove if possible-if not just bend them back out of the way.
90% of the time you can't reach any of the fuel or vapor lines without dropping the tank.
You should be able to drop the tank quite a ways and reach up through the gap.
Best way is to lower the jack slightly till your hand will barely fit and reach up and feel the lines/pump harness to see if it's stretched or not. Lower it till right before it starts pulling on them.
If it's lowered too far the disconnects will be a bear to get off,as you need to be able to push them in,then apply disconnect,then pull off-for most types.
You can stretch some pretty far,but you will almost always have to drop the tank to reach them.If you can drop one side further than do it,just gotta fight for the space.
Don't forget your wheelwell,sometimes removing a wheel can get you some room.
If the disconnects are being stubborn,try blowing them out with air and then spraying a hard stream of wd40 or similar into it. Dirt can play hell with disconnects.
Before you remove the fuel pump retaining ring,bang on the tank with a hammer and then blow off with air. Don't forget to put a rag in the fill hole also.
Get as much dirt off the pump top as you can so it doesn't fall in.
Always,Always,Always replace the filter and strainer with the pump,Always.
At work my boss knows I won't replace a pump without a new filter,refuse the job everytime.
I practice this on my personal vehicles also with no exceptions.
I also generally fill the filter up with seafoam when I install it.
When you get it back on the ground,put the pump relay back in,fuel back in and cycle the key 5 or 6 times to charge the filter and lines with fuel.
Should bust pretty much right off,might smoke a little on some vehicles if you used the seafoam-also run or idle rough depending on maintenance/condition.
Always use dielectric grease on the pump and FTP plugs,and not a bad idea to dab a little around the inside of the hose's and the oring's on the disconnects.


Hope that helps someone who is planning on changing their pump. It's not too terrible of a job and pretty routine after the first few. The right tools help alot,as does patience.
Glad yours went well schmeider.

[3400-95-Modified]

I read your other thread so I know you already got the new pump in but heres some answers in case others wondered.

Most of the time the straps and tank will be rusty,this is never a problem though.
Badly rusted bolts can snap and break,other than that they aren't an issue really.
On even the worse ones i've had some lube spray and my impact spin them right off.
I've never seen bands rusted so far as to need replacing,even on the most corroded,salted northern vehicles that have come through our shop (we're in the south.)

You must get very minimal northern vehicles then, or ones not used in heavy salt use states. Because I had to replace my straps, bolts, and tank from rust. One strap broke on me, and the bolts snapped off because they would not thread out of the clips, and the tank had multiple pin holes around the filler neck from salty rust, this all being exterior, there was not internal rust.

[Schmieder]

honestly, this seems like a ghetto way of going about it, but sometimes there are no alternatives....

let's consider that a 1-bar MAP will report ~2.2 volts at 50kPa. a 2-bar will report roughly half of that at the same amount of vacuum.

so: let's assume a VE of 50% at 2000RPM and 50kPa. with a 1-bar, we'll see 2.2volts from the MAP. let's also say that the engine is ingesting 50grams/second of air at this point. since a 2-bar would report ~half the voltage(and therefore, ~half the actual kPa), the engine would think it's at 2000RPM and 25kPa. so the actual value from the 2000/50 cell would need to be in the 2000/25 cell. intuition says that unless some funky reversion is happening, the 50kPa VE would be higher than the 25kPa VE, so i would expect to see higher numbers in the VE cells.

IMO anyway.

Thats the idea. I loose some resolution but not enough to be problematic.

These are the figures I have

Stock 1-Bar
20kPa = -14.70psi
30kPa = -12.86psi
40kPa = -11.02psi
50kPa = -9.19psi
60kPa = -7.35psi
70kPa = -5.51psi
80kPa = -3.68psi
90kPa = -1.84psi
100kPa = atmospheric

Install 2-Bar
20kPa = -14.70psi
30kPa = -11.02psi
40kPa = -7.35psi
50kPa = -3.68psi
60kPa = atmospheric
70kPa = +3.68psi
80kPa = +7.35psi
90kPa = +11.02psi
100kPa = +14.7psi

Knowing I will not push past 7psi my VE Tables will only be good up to 80kPa.

Question.....Will the PCM make and average between figures? i.e. if the MAP sensor is giving a voltage that would be 45kPa would the PCM use the value half way from 40kPa to 50kPa? Or would it use the 40kPa value until it reaches 50kPa?

[robertisaar]

that's called interpolation. i would be VERY surprised if the OBD2 PCMs didn't do it since ALL OBD1 ECMs/PCMs did.