I have a GTA 350 auto with HSR intake 22lbs injectors, I know its suppost to run at 38psi.
My question is, can the car run at 6 psi at all and whats the minimum it can run at?
Thank you

 

38 would be bare minimum on anything multi port FI Ive seen. No it cant run at 6 psi..unless youre talking about boost...lol

 

No boost here, all basic engine HSR setup.

 

It's an interesting question:

6 psi will never work. Keep in mind that an 'injector' is really nothing more than a port that opens and closes- and the amount of fuel pushed through is almost entirely dependant upon the pressure behind it. I don't know the limits of the ECM to hold the injector open- but it certainly won't be a wide enough range (and there won't be sufficient time in cam revolution) to allow for anything lower than maybe 30-35psi, assuming the injectors and fuel rails are totally unobstructed- and this assumes that you're just trying to get the engine to run, not run well.

 

It's been awile but I'am pretty sure the stock pressure should be around 42-44PSI.

 

Yup, stock TPI is 42psi

Why do you want to drop the FP? Is the car runnnig rich? Sounds to me like you just need some tunning.

 

No my friend.
Ive been have issues with this AcDelco engine for a while now.
Ive replaced most sensors my whole intake, this engine hasnt been running proper since day 1.
I have a year and few months left on my warrenty, and after going from shop to shop now all Im getting from 3 different mechanics is the bottom end of the engine is bad, knocking at idle and underload of course.
Timing is bang on, nothing more to do.
Now GM is avoiding the fact that the engine is defected, telling me at first the timing is off.
So I tell them to fix it, and they claim its too old a vehicle and they dont have the right tools do get it right.
After talking to the shop foreman, he agrees to look at it again to get it right.
Now my problem is the fuel pump, claiming it runs at 6 psi, this is after I replaced the faulty Holley regulator that was reading at 70 psi, which was replaced right away.
The car drives and runs under load no prob, just knocks and sounds rough, but now Im getting the run around from GM.
Getting tired of this, Im going up today again to argue this situation.
Ill keep you posted.

 

GM told you its 6psi the TBI's are 6psi not the TPI's

 

What crate engine? What year of car? SD or MAF? Stock was a 305 or 350?
What cam?

I have a small suspicion it still needs tunning, most performance/modded motors will run like a bag of crap on the stock chip

When I put my current motor in my car was so rich on the 305 chip the gas was pooring out the tail pipe's. Had to 2 foot it just to keep it running, bog'd like a ****, run's normal now that its tuned abit, even passed emisions. Just needs some tweeks.

But the motor might be screwed, its hard for me to say sitting in front of my computer and only reading what your saying, lol

 

87 Trans Am GTA 350 22lbs injectors, MAF with HSR intake, headers 3" cat back magnaflow muffler.
Changed IAC ,TB ,TPS, temp sensor, intake
Have both stock prom and performance prom, both knock either way.
New spark plug wires year old plugs rotor and cap, module was checked and is good.
Car runs and even pulls at high rpms, although Im told its running at 6 psi, I find it hard to believe since it doesnt bog out.
Since they claim it runs at 6psi they wont look into it further till fuel pump is replaced.
Its hard for me to believe that when checking my pressure before at 70 psi with a faulty regulator.
Im confused and dont know who to believe anymore, thing is if something doesnt need replaces then why replace it.

 

get a fuel pressure gauge and check it yourself.It shouldnt cost more than a mechanic's flat rate to check it.

TBI also run at around 15 psi not 6 psi.

 

That's the point of the whole exercise.

The warranty is 30 seconds or 30 feet - got it? If it blows up in the shop at install they'll do something - o/wise you're fuked.

They will probably just **** you around until you go away - what are you going to do - sue GM - fat fukin chance.

You can try customer service and you will be allowed to talk to someone who admits that they know nothing about technical matters but they can refer you to someone else in the US who you will never be able to get in touch with even if you were stupid enough to try.

Another thing is that certain information can't be released to the public - ie. leak down numbers.

Also, the rep for this area? - he's a dirtbag too.

Don't ask how I know all of this..lol

They are just production engines built by drunken workfare retards. If they run OK out of the box then they'll do alright but if they don't then you might just as well have got 3 tooth Cletus to build you a motor using parts from the wreckers.

 

Thanks for the positive post, very reassuring but probably true in your case.
I dont know who youve delt with but damn, bad experience I take it.
Im almost done replacing everything I need on my ignition system, nothing to the fuel lines or pump yet, although Im yet to check it AGAIN before replacing anything.
In this case if it doesnt fix the problem, there is nothing more that can be replaced or done.
They will have to honor the warrenty otherwise this will goto small claims for sure, been there before, it takes time but if your persistant and put up a good enough case you have a good chance winning, most people back out of the situation.
Theres no such thing as customer satisfaction unless you shop at Costco, return anything within the year warrenty, full money refund.

 

The problem with small claims court is that the cost grid blows so very few lawyers will want to take it on whereas GM can afford to retain counsel to jerk self represented litigants around so that in the end even if you win you lose.

Depends though, it makes sense for them to settle because their legal fees will exceed the cost of your claim but I've seen companies spend money to make an example out of people particularly in small claims matters so that the word gets around and other people get the message not to try it - I guess they see it as sort of like public relations in reverse..lol

Is the warranty parts and labour or just parts.

 

Warrenty is just parts.

 

Accel Analog Fuel Pressure Gauge Kits: ACC-74745 - summitracing.com

find out for yourself whats going on, and this way you can show them.

Auto Meter Sport-Comp Analog Gauges: ATM-3363 - summitracing.com

this is the exact one I run in my car with my HSR, a tad pricier then the other but I like having it in my car.

As for your superchip, on this forum sometimes is a guy called Stiffler, he dyno tested a hypertech chip on his 92 Z28. Did a run with the stock chip, popped it out and did a run with the hypertech. The results we not to die for.

I cant really help you tune as I have never done a MAF car, only SD car's, but even getting a lap top hooked on there with a scan program to log would tell a few things.

Is your chk engine light on? What codes?

Ya its a 350, what 350, what cam, is it a FI cam, what compresion ratio? Alum heads?

Remember GM has a dozen crate motors to pick from and not all will work well with a TPI.

Did you chk for any vacume leaks?

87 still has the cold start, did you get that eliminated? Try running a 89 chip, since your car's auto maybe you can talk Trigger into lending you one of his for a try.

 

I have 2 ecms just for backup, on has the stock 89 prom 350 auto gives no codes right now, the other is a custom prom for this setup but is giving code 41 42, although runs alot better than stock.
As for what 350, I wish I knew, even Ac Delco cant tell me, its a stock replacment for vin code "8" thats all I know and NOONE can tell me any further info about this engines parts.
No vacume leaks, confirmed...Cold start is off, no egr setup either, no smog, no ac, I removed everything just to eliminate any other potential problems.

 

Well defently take it easy on it till you get it figured out.

Poor feller at the dyno today had a car with some issue's, I heard it detonating from way over in the other room, so I came over to look but then.... well thank goodness for CAA at least.

Could of been anything from bad gas, bad tune to bad compression, bad build, really hard to say, I felt bad for him.

I'd just hate to see that happen to you well you try to get the bug's worked out.

As for your code's
41=Cylinder Select Error (Faulty or Incorrect Mem-cal)
42=Electronic Spark Timing (EST)

I can PM you a name of a place and the guy to talk to to get your car dyno tuned, they should be able to find and fix anyother problems too wile they are at it. Unfortunetly they're not overly cheap either. Just let me know.

 

Then its stock, nothing more or less, cast head's, pull off a valve cover, will be 083's(14101083) heads then. If not then it is not a stock replacment.

Needs a head and cam change when you can aford it for more power, the HSR can flow alot more RPM over the stock LTR TPI. Trigger dyno'd 292rwhp today with his HSR 355ci, AFR heads, LT4 hotcam and near stock tune.

As for the cam that should be in there now, depends what year of "8" vin code 350 they used, most likely the first one if its for your year
1987 Roller #14093643 Int/Exh 202/207 Lift .404/.415
1988-89 Roller #10066049 Int/Exh 207/213 Lift .415/.430
1990-92 Roller #10111773 Int/Exh 202/207 Lift .413/.428

Either way, all 3 cam's would work fine drive wise.

 

Ac Delco part number: 12465201
Another thing that bothered me, when I got the engine, the knock sensor hole was too big, so the dealership told me just to heli coil the knock sensor.
I had to use my valve covers because the ones on the new engine were the other way (holes for oil ).
My mechanic was rather suprised that they would recommend that, but since the engine was almost complete in the car I wasnt going to pay for this one to be pulled again. The dealership wouldnt cover that.
As long as you can recommend a good place in the Hamilton area, please do.