redding
Newbie
Posts: 3
Reg: 05-24-23
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05-24-23 10:16 PM - Post#2858294
Hello all,new member from md,as stated in title Ive got a 93 tbi 1500 with 4.3 Lb4 z engine,bought it in 2014,put at least 150k on it,always changed oil when dirty,only minimal problems all these years,typical stuff,starter,cap/rotor etc....
Just recently got the code 32,did the tbi kit,new egr(this truck uses the what manual calls Linear egr,it bolts to the neck of the intake at the back below the fuel lines),cleaned everything real good and ran great for a week then back to the hesitation,very poor acceleration,just overall running bad.
I can unplug the map and egr and it does nothing,blocked of the the egr and still same thing,tested continuity of wires with a signal tracer,everything seems to check out but I dont know.
I can tell you both exhaust manifolds have broken bolts but its ran that way for a good while,its a work truck and tho dented up has no rust which around here is uncommon being close to the ocean.
My questions are..
1.how to go about testing this type of egr with a meter(I'm good with using meter need to know what to look for).
2.being that unplugging egr and map does nothing do you think I have clogged up exhaust return ports or maybe air getting to 02 sensor causing issues?
Its odd it ran fine for a week then right back to the way it was,in the past Ive had ecm give its last hurrah like this,work great then give up the ghost.
Any pointers or input from anyone whos had same issues with said motor would be awesome 
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 Shepherd
Valued Contributor
Posts: 2972
Loc: Lake George, NY
Reg: 11-11-15
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05-25-23 06:31 AM - Post#2858308
In response to redding
Unplugging the map should drive it to full rich.
Egr should not affect performance unless stuck open. Have you scanned it and looked at o2 sensor activity, any exhaust back pressure can cause problems, such as a partially restricted cat. Low fuel pressure another possibility.
Edited by Shepherd on 05-25-23 06:33 AM. Reason for edit: No reason given.
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redding
Newbie
Posts: 3
Reg: 05-24-23
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05-25-23 07:51 AM - Post#2858309
In response to Shepherd
hi shepherd,its a 93 so only has the aldl,not sure how to go about using a scan tool on some thing this old.
I had just replaced the fuel filter a few days ago would have been a good time to check pressure but I didnt :sad : should have since checking on these years with no pressure port is a pain to put it lightly.
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Shepherd
Valued Contributor
Posts: 2972
Loc: Lake George, NY
Reg: 11-11-15
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05-25-23 07:59 AM - Post#2858310
In response to redding
You can get an obd1 scanner cheap on bay. Good thing to have, make sure you get the cable too.
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 someotherguy
Senior Moderator
Posts: 29696
Loc: Texas
Reg: 08-01-03
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05-25-23 02:21 PM - Post#2858328
In response to redding
hi shepherd,its a 93 so only has the aldl,not sure how to go about using a scan tool on some thing this old.
I had just replaced the fuel filter a few days ago would have been a good time to check pressure but I didnt :sad : should have since checking on these years with no pressure port is a pain to put it lightly.
If you're going to own/maintain a TBI vehicle yourself, you should invest in a decent fuel pressure test kit. Actron makes one that comes with the special fitting for TBI's; if you only have your truck to worry about and nobody else's, you can leave the fitting installed permanently. I used an A/C service port cap (fits perfectly) to keep dirt out of the valve on mine. It can go under the truck by the filter, or behind the TBI unit though that usually requires a little work to loosen the fuel line bracket where it attaches on the bellhousing stud so you can get a little slack in the line so the fitting can go in. In the pic is a different brand gauge I'm using with the Actron fitting.
The Actron kit # CP7818 has everything BUT the TBI adapter which is their part # 0180-000-1465 or you can get their "professional" kit which is # CP7838, includes the TBI fitting. I've seen that fitting offered by itself from other sellers for $30 and higher, don't spend that much, it's about $15 now (used to be $10)
The CP7838 which includes the fitting is only $56 at amazon right now. Not a bad price for a gauge kit with pressure release valve/hose, and includes the TBI adapter.
Richard
| 06 Silverado ISS / 06 Silverado SS / 06 300C SRT8 / 93 C3500 dually |
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Tony1963
Frequent Contributor
Posts: 2246
Loc: Orlando Florida
Reg: 07-09-18
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05-25-23 03:48 PM - Post#2858333
In response to redding
GM used a pretty robust computer system in those models - it is referred to as an OBD I system (onboard diagnostics version 1).
The best tool that I have found, other than an old GM Tech tool, is a Snap On MT2500 "brick" scanner. One of those can read all of the data and codes.
Otherwise, you are guessing.
| People fear change because it threatens what they know, or what they claim to know. |
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thx1138v2
Contributor
Posts: 253
Reg: 05-01-14
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05-26-23 07:02 PM - Post#2858391
In response to someotherguy
"...any exhaust back pressure can cause problems, such as a partially restricted cat."
I have a '94 4.3L with catalytic converter. I was having similar problems with it and I pulled the exhaust system loose from the headers and took it apart. I found the catalytic converter canister somehow got turned sideways in the housing. I took a 3 foot steel rod and knocked the canister out of the housing, put it back together and all kinds of things were suddenly corrected.
I was broke at the time so drove it like that for a while and later put a new catalytic converter on it and it has continued to run good.
It just turned over 257K miles recently.
So it might be worth a look. If you know what the exhaust pressure feels like normally you might could put your hand across the end of the exhaust pipe (while it is cold at first startup) to feel the pressure to determine if it is low. That would also indicate a plugged exhaust system.
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