LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Anyone have any ideas?

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Old 07-23-2010 | 09:13 AM
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Anyone have any ideas?

First things first engine light is on its been on just got a quick questions any ideas as to what could cause the following. ( I will be putting a computer on) I just wanna know if anyone knows "Hey oh yeah thats this part doing this" kind of answers.

In accelaration throughout the rpm ranges (all of them) especially going up hill when giving gas instead of a smooth coast through the rpm ranges it seems like its going through stages of power. In example up hill from a stop sign light gas makes it coast up slowly almost lacking power. Then more gas seems to jump to a whole different level of power. Full throttle seems like it takes a minute to find that power and then takes off to another level of power. There is no smooth accelaration at times and at other times it seems decent enough.

Was going to buy a fuel pressure guage this weekend and get exact numbers of pressure (my friend who had one dissapeared on me). I am thinking it is a fuel pump issue or FPR issue, I guess my questions is would it cause this kind of issues?

Also need link to nice OBD1 scanner and ALDL cable for serial port, todays payday so Id really like to get some good info/links today to get my shopping out of the way. Thanks everyone in advance.
Old 07-23-2010 | 09:19 AM
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You're on the right track with checking fuel pressure and getting it scanned.

When the engine is under load, there is more cylinder pressure. If there are any weak plugs or ignition components, they will rear their ugly head and will cause a lack of power.

Check www.akmcables.com for the cable you need. Download Datamaster for free and you're good to go.
Old 07-23-2010 | 09:34 AM
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Originally Posted by RamAir95TA
You're on the right track with checking fuel pressure and getting it scanned.

When the engine is under load, there is more cylinder pressure. If there are any weak plugs or ignition components, they will rear their ugly head and will cause a lack of power.

Check www.akmcables.com for the cable you need. Download Datamaster for free and you're good to go.
Thanks or the quick response! I really appreciate that, and its good to know it does sound like it could be a fuel issue? Cant wait to get all this stuff going.
Old 07-23-2010 | 09:36 AM
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Originally Posted by Chaos1187
Thanks or the quick response! I really appreciate that, and its good to know it does sound like it could be a fuel issue? Cant wait to get all this stuff going.
Maybe, maybe not! No use in speculating, so go get that fuel pressure gauge.
Old 07-23-2010 | 09:48 AM
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This is the port on my laptop please tell me this is what i need...


Old 07-23-2010 | 10:00 AM
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That's a serial port. The older style cables will work with them (I have one of those). Most of the newer cables use USB. Just email Andrew and make sure your cable comes with a serial port adapter.
Old 07-23-2010 | 10:05 AM
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Ok thanks again I got the USBs of course but have heard great things on the serial just didnt know cuz the cable pins throw me off.
Old 07-23-2010 | 10:33 AM
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Originally Posted by Chaos1187
This is the port on my laptop please tell me this is what i need...

That's a video port-not a serial data port.

This is a serial data port.

Old 07-23-2010 | 10:49 AM
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Originally Posted by shoebox
That's a video port-not a serial data port.

This is a serial data port.
So would i get a usb cable one then shoebox? What programs any issues because i understood there was issues with those cables? Would i be better of buying an OBD1 Scanner?
Old 07-23-2010 | 11:56 AM
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Originally Posted by Chaos1187
So would i get a usb cable one then shoebox? What programs any issues because i understood there was issues with those cables? Would i be better of buying an OBD1 Scanner?
Injuneeeeeer should i use the ALDL usb cable? Or buy that OBD1 you had recommended??
Old 07-23-2010 | 12:02 PM
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Use EXACTLY what Andrew at AKM Cables tells you to use. He is the expert.

I'm not sure what you mean when you say "buy that OBD1 you had recommended".... I may have provided you with info regarding a hardware OBD-I scanner, or I may have provided you with links to the correct OBD-I software and the cable. Either will pull the codes. But given a choice, I would recommend you use FreeScan or DataMaster, to provide a data log that will document what happens to the engine when you put it under various throttle loads.
Old 07-23-2010 | 01:20 PM
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Originally Posted by Chaos1187
So would i get a usb cable one then shoebox? What programs any issues because i understood there was issues with those cables? Would i be better of buying an OBD1 Scanner?
As far as cables, it depends on what ports you have available on your computer. If you change computers later, it very well may not have a serial port to use. Your choice.
Old 07-23-2010 | 03:06 PM
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Thank you Injuneer, Shoebox and everyone else on here for your help I know I will come to learn a lot from all of you. I appreciate everyones patience with my ignorance on a lot of my questions.
Old 07-24-2010 | 07:58 AM
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Okay I put the fuel pressure guage (Made me happy to buy a new tool ) on the fuel valve turned key on engine off read about 42psi and within 3 to 5 seconds tops no pressure at all. Tried it about 10 times all together did it the first five time it held pressure one time. Then key on engine on pressure dropped to about 38psi shook back and forth give or take 1psi. Turned key on engine off pressure next 5 tries did same thing within 3 to 5 tops no pressure at all. I believe it to be the fuel pump, any input is helpful thank you in advance. =)
Old 07-24-2010 | 12:13 PM
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Originally Posted by Chaos1187
Okay I put the fuel pressure guage (Made me happy to buy a new tool ) on the fuel valve turned key on engine off read about 42psi and within 3 to 5 seconds tops no pressure at all. Tried it about 10 times all together did it the first five time it held pressure one time. Then key on engine on pressure dropped to about 38psi shook back and forth give or take 1psi. Turned key on engine off pressure next 5 tries did same thing within 3 to 5 tops no pressure at all. I believe it to be the fuel pump, any input is helpful thank you in advance. =)
With the data you provided, you either have:

-Leaky fuel pump check ball
-Leaky fuel pump flex hose
-Leaky fuel pressure regulator
-Leaky fuel injectors

The regulator is the easiest thing to check. Disconnect the vacuum line on the back of the regulator and prime the pump. If fuel comes out of the regulator, the diaphragm is torn and needs to be replaced.

If the regulator checks out okay, then it's time to move on to the injectors. Remove the four bolts holding the fuel rails down and pop out the fuel lines with the injectors still attached. Prime the fuel system while carefully looking at the injectors. If any of them leak, you've got a stuck/leaky injector that must be replaced.

If both of those check out okay, it's fuel pump time.


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