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Discussion Starter · #1 ·
Hello all, the past 6 months I have been enjoying gleaning from many of the existing threads as I have been doing a very low budget "restoration" on a trashed 92 2.8TBI 5spd s10 with 135,000m. I was gifted this truck by a someone who used it as their daily and was heavy on the gas pedal. When it became undrivable they passed it along to me. I picked it up gladly wanting the troubleshooting experience. I am a low-time aircraft mechanic and wanted to learn how automotive systems work. If I can get this vehicle to a reliable state, I would like it to replace my current rustbucket honda. In the suspension and driveline department I have had all successes, and it handles much better on the road, but now I'm getting a real headache trying to get the engine back up to snuff.

My issues remaining are horrible fuel consumption (estimating less than 10 mpg), dies at idle (especially when warm), surges lightly when cruising, occasionally backfires and stumbles at highway speed. Not sure what to be expecting in the power department, but this thing doesn't have the guts to spin a tire in first or maintain speed in 5th on the highway with the slightest upslope. If I drive it in "field service mode" with the jumper in the obd-1 connector it seems to help the surging and idling issues significantly.

I've already done new plugs/wires/rotor/cap/coil, lots of cleaning and peripheral sensor/wiring/gasket type stuff. IAC was replaced. I had put off doing a compression test until today but now I am beginning to wonder if that was a dumb move. Results:
Cyl.-- dry: --with tablespoon of oil:
#1 - 160 --240
#2 - 162 --186
#3 - 150 --200
#4 - 140 --186
#5 - 102 --184
#6 - 124 --150

first automotive compression check I've done so I could have made a mistake somewhere but I'm confident most of those numbers are accurate. here's a pic of the plugs after 30 miles. #5 seemed to be turning a different color than the rest.
Automotive tire Automotive lighting Audio equipment Automotive exhaust Automotive wheel system

I'm pretty sure #4 was bent after removal.
My question, is there any thing else I can do to be sure my engine is toast before I condemn it to a rebuild or start hunting for a donor vehicle. If I'm seeing things right, I've got bad rings and no amount of peripherals are going make this engine healthy without a rebuild. I am rather confused why the jumper would make it run better. My understanding is that this affects the computer controlled timing of the ignition system.

if any other data is needed or this is a stupid question, let me know.

thanks!
 

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Not necessarily bad rings. Could be bad valves, cam, lifters or bent push rod since the PO liked beating on it.
Pull the valve covers and take a look. If nothing, pull the heads and valves.
BTW doing the necessary tests to locate a problem is never a dumb move.
 

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Discussion Starter · #3 ·
any input on what to look for under the valve covers? I had them off a month ago and didn't see anything obviously loose, broken, or clogged. no ticking that I can hear over the fan.
I don't have the budget to do a full overhaul at the moment so I'd like to have an idea what is bad before I start pulling the heads. I may try getting my hands on a differential compression tester.
 

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Discussion Starter · #4 ·
I did not feel right about that compression check so I did a makeshift leakdown test by applying 80 psi to each cylinder while at tdc and listening for the source of escaping air. each cylinder was hissing mostly through the crankcase and just a tad through the exhaust. they all sounded about the same so I started getting suspicious of my initial compression check. today I watched a number of videos on how to do a automotive style compression check properly. I got a few pointers and went at it again. this time cranking a bit longer and watching the gauge to make shure the needle pulsated through 7 revolutions. I also found a bit of carbon preventing the tool from sealing on a couple cylinders. with those fixed my new readings are all 165psi except #1 @ 167 and #5 @ 160 and rising to 165 at ten revolutions. this time I did the test with a cold engine. Unless the temperature made the difference, I do not think compression has anything to do with my problem.
I am back to troubleshooting and will exchange my rental tool for a fuel pressure tester. any recommendations on supplemental resources to use for that test? any newbie mistakes to avoid?
 

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Discussion Starter · #5 ·
For anybody down the road with similar problems, here's the diagnosis on this case. After the compression check came back good I got a fuel pressure tester. It told me I have 10.3 psi anywhere from idle to wot takeoff on the road. feeling stumped, I decided to recheck my ignition timing. Well, to my dismay it had crept to about 25*btdc. Apparently, I messed up while resetting it after I put the engine on this spring. now it idles fine and has significantly more torque. Still got other issues to solve, but the big ones are out of the way
 

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For anybody down the road with similar problems, here's the diagnosis on this case. After the compression check came back good I got a fuel pressure tester. It told me I have 10.3 psi anywhere from idle to wot takeoff on the road. feeling stumped, I decided to recheck my ignition timing. Well, to my dismay it had crept to about 25*btdc. Apparently, I messed up while resetting it after I put the engine on this spring. now it idles fine and has significantly more torque. Still got other issues to solve, but the big ones are out of the way
Glad you figure it out! Those compression numbers are really good for an old 2.8. Compression tests tell you a lot about the health of the motor. I don't think you have too much to worry about with that.
 

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Hello all, the past 6 months I have been enjoying gleaning from many of the existing threads as I have been doing a very low budget "restoration" on a trashed 92 2.8TBI 5spd s10 with 135,000m. I was gifted this truck by a someone who used it as their daily and was heavy on the gas pedal. When it became undrivable they passed it along to me. I picked it up gladly wanting the troubleshooting experience. I am a low-time aircraft mechanic and wanted to learn how automotive systems work. If I can get this vehicle to a reliable state, I would like it to replace my current rustbucket honda. In the suspension and driveline department I have had all successes, and it handles much better on the road, but now I'm getting a real headache trying to get the engine back up to snuff.

My issues remaining are horrible fuel consumption (estimating less than 10 mpg), dies at idle (especially when warm), surges lightly when cruising, occasionally backfires and stumbles at highway speed. Not sure what to be expecting in the power department, but this thing doesn't have the guts to spin a tire in first or maintain speed in 5th on the highway with the slightest upslope. If I drive it in "field service mode" with the jumper in the obd-1 connector it seems to help the surging and idling issues significantly.

I've already done new plugs/wires/rotor/cap/coil, lots of cleaning and peripheral sensor/wiring/gasket type stuff. IAC was replaced. I had put off doing a compression test until today but now I am beginning to wonder if that was a dumb move. Results:
Cyl.-- dry: --with tablespoon of oil:
#1 - 160 --240
#2 - 162 --186
#3 - 150 --200
#4 - 140 --186
#5 - 102 --184
#6 - 124 --150

first automotive compression check I've done so I could have made a mistake somewhere but I'm confident most of those numbers are accurate. here's a pic of the plugs after 30 miles. #5 seemed to be turning a different color than the rest.
View attachment 351397
I'm pretty sure #4 was bent after removal.
My question, is there any thing else I can do to be sure my engine is toast before I condemn it to a rebuild or start hunting for a donor vehicle. If I'm seeing things right, I've got bad rings and no amount of peripherals are going make this engine healthy without a rebuild. I am rather confused why the jumper would make it run better. My understanding is that this affects the computer controlled timing of the ignition system.

if any other data is needed or this is a stupid question, let me know.

thanks!
80 lb bounce on 5 sez rings/cyl wall suspect. About as good a reason not to waste a dime on inadaquat 2.8. SBC or LS type transplant is best bang for about same bucks.
 

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Awww..you ain't got shit!
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80 lb bounce on 5 sez rings/cyl wall suspect. About as good a reason not to waste a dime on inadaquat 2.8. SBC or LS type transplant is best bang for about same bucks.
Really bad advice. Could not disagree more on this. First, he stated that he found out why he had those kinds of readings in the last post and now the truck runs fine. Secondly, a 2.8 can actually make "decent" power when allowed to breathe, having a proper cam and good tune. So it is more than adequate for daily driving (which is what he intends to do). Third, while you may say it's cheaper to do a V8 conversion, unless you throw thousands at it to properly upgrade the steering and suspension as well, it isn't cheaper at all. After 29 years those components are trashed. Skip that, and what you wind up with is a hacked up, ill handling and completely unsafe deathtrap that's significantly harder to work on. I know this because my uncle and I did one a long time ago. Gobs of power? Yes. Fun to drive or safe? Hell no! Terrifying hacked up pile of crap. Fourth, a V8 swap isn't for the faint of heart, and a lot of these never get completed due to complexity.

The most affordable and practical upgrade is a 3.4 from a Camaro or Firebird, or the 3.4 crate (unlikely you will find one). It's drop in and go (mostly) since physically it's the same thing as the 2.8. With headers, hot rodded fuel injection, efan and a few other goodies, my truck can keep up with a 305 SBC easily which to me is decent performance. Gets decent mileage too. Handles like stock, because it mostly is. It also wrenches like stock, and parts are standard shelf stuff for the truck. Uses the same transmission the truck had before and the stock driveshaft too. I updated my suspension on my truck too when I lifted it. Now what I have is a mostly stock truck with a significant power upgrade that's a joy to drive and service. No offense man, but I get so tired of these "man, put a V8 in it comments" as the best solution for "bang for the buck" when there are definitely more options than the trouble and expense of a V8 swap.
 

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Hello all, the past 6 months I have been enjoying gleaning from many of the existing threads as I have been doing a very low budget "restoration" on a trashed 92 2.8TBI 5spd s10 with 135,000m. I was gifted this truck by a someone who used it as their daily and was heavy on the gas pedal. When it became undrivable they passed it along to me. I picked it up gladly wanting the troubleshooting experience. I am a low-time aircraft mechanic and wanted to learn how automotive systems work. If I can get this vehicle to a reliable state, I would like it to replace my current rustbucket honda. In the suspension and driveline department I have had all successes, and it handles much better on the road, but now I'm getting a real headache trying to get the engine back up to snuff.

My issues remaining are horrible fuel consumption (estimating less than 10 mpg), dies at idle (especially when warm), surges lightly when cruising, occasionally backfires and stumbles at highway speed. Not sure what to be expecting in the power department, but this thing doesn't have the guts to spin a tire in first or maintain speed in 5th on the highway with the slightest upslope. If I drive it in "field service mode" with the jumper in the obd-1 connector it seems to help the surging and idling issues significantly.

I've already done new plugs/wires/rotor/cap/coil, lots of cleaning and peripheral sensor/wiring/gasket type stuff. IAC was replaced. I had put off doing a compression test until today but now I am beginning to wonder if that was a dumb move. Results:
Cyl.-- dry: --with tablespoon of oil:
#1 - 160 --240
#2 - 162 --186
#3 - 150 --200
#4 - 140 --186
#5 - 102 --184
#6 - 124 --150

first automotive compression check I've done so I could have made a mistake somewhere but I'm confident most of those numbers are accurate. here's a pic of the plugs after 30 miles. #5 seemed to be turning a different color than the rest.
View attachment 351397
I'm pretty sure #4 was bent after removal.
My question, is there any thing else I can do to be sure my engine is toast before I condemn it to a rebuild or start hunting for a donor vehicle. If I'm seeing things right, I've got bad rings and no amount of peripherals are going make this engine healthy without a rebuild. I am rather confused why the jumper would make it run better. My understanding is that this affects the computer controlled timing of the ignition system.

if any other data is needed or this is a stupid question, let me know.

thanks!
Senor Kicker , Many thanks for your through 'Dressing Down' . Don't know of anyone whom woulld't appreciate your classic tact. Haircut over the phone diagnosis was based on the presented 'accurate test numbers' , not the fiction they actually were. ?That said , good to know all's well and running perfectly. I
 

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Really bad advice. Could not disagree more on this. First, he stated that he found out why he had those kinds of readings in the last post and now the truck runs fine. Secondly, a 2.8 can actually make "decent" power when allowed to breathe, having a proper cam and good tune. So it is more than adequate for daily driving (which is what he intends to do). Third, while you may say it's cheaper to do a V8 conversion, unless you throw thousands at it to properly upgrade the steering and suspension as well, it isn't cheaper at all. After 29 years those components are trashed. Skip that, and what you wind up with is a hacked up, ill handling and completely unsafe deathtrap that's significantly harder to work on. I know this because my uncle and I did one a long time ago. Gobs of power? Yes. Fun to drive or safe? Hell no! Terrifying hacked up pile of crap. Fourth, a V8 swap isn't for the faint of heart, and a lot of these never get completed due to complexity.

The most affordable and practical upgrade is a 3.4 from a Camaro or Firebird, or the 3.4 crate (unlikely you will find one). It's drop in and go (mostly) since physically it's the same thing as the 2.8. With headers, hot rodded fuel injection, efan and a few other goodies, my truck can keep up with a 305 SBC easily which to me is decent performance. Gets decent mileage too. Handles like stock, because it mostly is. It also wrenches like stock, and parts are standard shelf stuff for the truck. Uses the same transmission the truck had before and the stock driveshaft too. I updated my suspension on my truck too when I lifted it. Now what I have is a mostly stock truck with a significant power upgrade that's a joy to drive and service. No offense man, but I get so tired of these "man, put a V8 in it comments" as the best solution for "bang for the buck" when there are definitely more options than the trouble and expense of a V8 swap.
Senor Kicker , Many thanks for your through 'Dressing Down' . Don't know of anyone whom woulld't appreciate your classic tact. Haircut over the phone diagnosis was based on the presented 'accurate test numbers' , not the fiction they actually were. ?That said , good to know all's well and running perfectly. I
 

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Awww..you ain't got shit!
Joined
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3,613 Posts
Senor Kicker , Many thanks for your through 'Dressing Down' . Don't know of anyone whom woulld't appreciate your classic tact. Haircut over the phone diagnosis was based on the presented 'accurate test numbers' , not the fiction they actually were. ?That said , good to know all's well and running perfectly. I
No offense meant on that Pete. I hope you didn't take it that way. Simply stating that a 2.8 can actually make good power. My 84 with the Edelbrock intake, the 4bbl, headers and e-fan also made really decent power compared to the stock setup. I mean to the point of being in shock that this was the same slug it was stock. It did run out of steam in the higher RPMs but it was a HUGE improvement. The 3.4 also had even better performance with the 4bbl and with the fuel injection made almost unbelievable power for the displacement. Just saying that "I could have had a V8" is far from the only realistic option to an old tired 2.8 truck to make power.
 
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