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· square body man
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218 Posts
Discussion Starter · #1 ·
not to brag, just here to help... any questions or unsolved mysteries? i can just about answer anything about these little engines- i love them, i have owned 23 lol -
 

· square body man
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218 Posts
Discussion Starter · #2 · (Edited)
a little engine info-

fuel problems! dont we hate them?
most of the studdering and cold weather issues and hard starting derive from this issue. most fuel issues come from when a s-10 sits for a while or a fuel pump goes down. the plastic/foam pipe that connects it is usually eaten up in the process of the transformation from gas to turpintine. then, most people unknowingly (like me) change the fuel pump and try to crank it, throwing that gunk into the throttle body, which basically has the same affect of sugar. in the process, it travels past the fuel filter, into the tbi, with no problem, and is partially burned away. the rest tries to make its journey back to the fuel tank, but is stopped at the fuel pressure regulator and is built up along the bottom edge of the rim. fuel the pressure regulator is at the side of the tbi on top, it has 4 torx bit screws that retain it. simply clean it and it will help alot. as for the IAC get trash also, so it should be removed and cleaned and adjusted. it is on the passenger side at the bottem with 2 torx bits retaining it with a small harness. the extention and nozzle should not extent more than 1 inch passed the plastic housing. tpi sensors do go bad and autozone does test them. as far as missing, or lean fuel, the hall effect in the distributer wears out also. it picks up a magnectic current to open and close the injector. sometime those little tanges rust and it doesnt pick up the signal as well as it should. sand paper and wd40 fixes that. the hall effect is under the rotor button and can be removed with a 5.5 mm socket, two small boths with a pigtail harness with three prongs. it also varies the amount of fuel consumption in conjunction with the mat/map. explains poor fuel mileage.
injector issues, leaking or dripping injectors- there are two rubber o-rings that dry-rot after a while without running. one small at the tip of the injector, which no book depicts how it is to be placed, and the top one, that has a grove for it, which i havnt seen that one go bad yet, but the bottom one fails alot, causing rough idle and poor compression on the #4 cylinder because of leaking fuel and washing the cylinder wall.


some much for fuel

erg system
erg valves get stopped up alot, causeing rough or high idle and poor operating conditions. quick way to test it! first remove it. remove the breather, and get a 1/2 in wrench. open end part, remove the two bolts that retain it and dont break the vacuum line in half, they are hard to find. take it off and suck the vacuum hose with your mouth, usually you can hear it actuate. if not, its stopped up. clean it good or replace it.
2.5 will smoke it the egr system is not hooked up properly. one big metal line from the valve cover to the side of the tbi, make sure it is not stopped up and the pcv (positive crank case ventilation) valve is not all gooed up. next, which is not orthodox, i prefer to plug the second pcv port that runs to the breather, on the back of the valve cover. i have expirienced better gas mileage doing that and the vacuum is stroger in the crank case which removes stress from the main seal to aid is the loss of leaks. nothing more to say here.


timing, pain in the ass, inductive type light, 8* btdc

idle
idle is sometimes high, due to the little idle screw backing off. attach a tach to the negative wire to the dist. and get ready to adjust! the screw location is located beside the IAC, but its hidden behind a little backout preventer which will have to be punched out to be adjusted, small phillips head does the trick evey time. should be adjusted to around 600 rpm or what your under hood sticker says to adjust to.
check your erg valve first before any adjustment.

MAP sensors do go bad but still function somewhat. best thing to do is remove it and take it to get it tested at autozone. keep in mind, autozone does not charge to test it. replace because there is no adjustment.


valve noise
very rare in my opinion. valves cannot be adjusted, only replaced. if you have a sound like a tap, its one of two things: cam gears or a lifter not priming. i covered the timing gears below. valve seals are a common problem, leaking and causing a fuss with smoking and burning oil. how to change them: remove the breather, remove the valve cover with a 10 mm socket. remove the spark plugs and take off the battery cable. start with cylinder 1, turn it so that it is tdc (top dead center) and find a about 5 foot of 1/2 inch rope. turn the cylinder so that it opens a little, about half a stroke. fill the cylinder with rope and LEAVE ONE END HANGING OUT, trust me. turn the engine so the it compresses the valves up on the compression stroke, threfore, making your valves stay seated without compression! take a spring comressor lever (i make mine) and compress your springs, remove the keepers with a magnet and DO NOT DROP IT!, pull the valve seal and buy you some new ones, replace the sping and keepers put everything back together and your done! no more leaking without removing the head!

cam gears-
sound like a lifter worn out, ya know, tap tap tap tap at an idle... get the haynes manual for this one!

any questions?
 

· Rarely goes over 20mph
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3,148 Posts
i recently have been getting horrible gas mileage.

i took my cat converter off in the spring, and ever since, it started sounding worse and worse. from the exhaust tip, it sounds like popcorn inside the exhaust, it just sounds like popcorn popping, and it keeps getting worse.

check engine light was on and n oone could help me, so i took it to the dealership, $250 fo rifx ignition module, and it still did it, but then the engine started knocking and it kept dying on me, took it back, they replaced egr valve, still knocked. so i went and bough ta new ECM, because on the way home it acted up, the SES light came on, started flashing at me, random flashes some slow some super fast, no pattern. hasnt done it since.

then my engine overheated 250F, so we replaced head gasket, intake, exhaust gasket, water gaskets, spark plugs with acdelco, and it ran good, but i checked my mileage, going 55mph, i got 14.9mpg

when i got 28.9mpg going 65 :rolleyes:

we tried to hand turn the crankshaft with a socket wrench, and we couldnt even move the crankshaft, it was bound up and didnt want to move, but yet it moved before.

so far it drives great and acts normal, but its using ALOT of gas. i topped it off, and ive gone 40 miles and im 1/16th past full, so its used up about 1/8th of a tank? 13 gallon.

the mileage has been getting worse and worse, i remember it being at 18mpg once.

it baffles me because ive replaced so much of my engine that the only thing that i can think of, is the cat converter not being on is getting me bad mileage and making my exhaust sound like popcorn at idle.

it doesnt idle high, its timed at 8* btdc, heres what ive replaced

spark plugs,wires,cap,rotor, ignition module
tps sensor
map sensor
exhaust manifold, straight piped to a super turbo no cat
serpentine belt
electric fan-was on when i was getting 28mpg highway
battery
starter
radiator
head gasket,intake gasket, exhaust gasket, valve cover, water gaskets
IAC was cleaned out twice
egr valve-dealership put in
air filter, fuel filter, oil filter, 10w40 oil
35psi in tires, same as when i was getting 28mpg

im thinking the cat converter is the main problem.

when i bought the truck, the stock front coolant temp sensor was unplugged and an aftermarket water temp gauge was hooked in. the dash coolant gauge kept fluxuating so much it would go from 100* to 280* so fast it would make a ticking sound. so i rehooked up the old water temp sensor, and it didnt make any diffrence. the gauge doesnt work at all.

ill have to check mileage for city this weekend, i only drive it 25 blocks a day, so its not like i drive it very far.


this spring, im gonna have a cat converter welded in, get a new ignition coil and spark plug wires, and both coolant temp sensors.

the truck runs great, just gets horrible mileage
 

· square body man
Joined
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218 Posts
Discussion Starter · #4 ·
well, does your engine vibrate any? auto or manual? check the harmonic balancer if it has one- some do, some don't. the go bad if it is equiped and it will throw off a bunch of things too
try one thing for me and i can tell you alot of things by this-
take out all you plugs, then rotate the crankshaft by hand, any resistance? any grinding? noises? air, unusual smells like burned metal?

when was the last time you changed your oil? did it have metal shavings? or gunky like material?
 

· Rarely goes over 20mph
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3,148 Posts
changed oil 2-3 weeks ago, had 700 miles on the oil before i changed it, we changed the head gasket and changed oil and filter before we started it up.

oil was fine, no water in it or anything. looked good enough you could almost put it back in, minus it being dark brown, not black. no metal shavings, no gunk, nothing.

i just took the crankcase breater tube off, started it up, and it ran like it normally does, just a HAIR better, the exhaust sound went away HALFWAY, its still there, but at idle, it actually sounded like a v6 instead of a popcorn machine, it still has it, but not as badly.

on revving up, its got a slight whooshing sound, like the sound a fan makes. which leads me to beleive its because of no cat=no back pressure=whooshing air.

my engine does vibrate a little bit on start up and when you turn it off, whole truck moves on shut down.

its a 5 speed, 99915 miles

the main thing that made me and my father change head gasket, was it overheated, and there was some yellowish clear liquid inside the air filter, coming from the crankcase breather. i was told its just condensation.

when i blocked off the crankcase breather, the engine didnt really vibrate at all, it has a ticking noise thats been there since i bought it, havnt been able to find where its from.

the valves on the cylinder side looked brand new other than being black, no damage or sign of hitting.


the truck runs and drives fine, its just not getting as great of gas mileage, and the exhaust sound is embarrasing

i dont have anywhere to work on it, so doing something like taking out spark plugs and checking that wont happen till spring, im open to ideas, its not that big of a deal right now, becuase like i said, i drive it 25 blocks a day, on weekends i dont even drive it unless i need to, so $15 lasts me 1 1/2-2 weeks, in the summer $25 would last me a week, cause i drove it all over nonstop
 

· Registered
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685 Posts
Ill let you know if I need you shortly. I was having a few problems. Also, my work just got a modis scanner from snap-on, Im learning how to use it on my truck. I was having rough idle when cold, then high idle when warm. also, my timing would jump around while trying to time (10-20 degrees in either direction) I replaced the map because even with the vacuum line unhooked, i was still getting jumpy readings. That straightened up my timing problem. But today it acted up again, and I got a check engine light for low circuit or short in coolant temp circuit. So I hooked up the modis and low and behold i got 300* C in the motor (whats that like 600*F?) I just replaced the coolant temp sender in the front of the motor with a brand new GM one, so I know thats good. I actually cut the 2 wires going to the ECM and it still read 300*C. So i ran the service numbers on the ECM, low and behold its for a freekin trans am with a TPI 305. The idiot that worked on it before me replaced every single electrical part on the truck except for the bad one, sometimes replacing them with the wrong one (coolant temp sender and ECM) So Hopefully the junkyard is open tomorrow. HERES ONE FOR YA RIGHT NOW!!!! Can I use any ECM with a 2.5 manual for this truck? I was picking through a Fiero with a 2.5 in it. For the 1st time in 5 years the closest j-yard to me had no s-10s or blazers! Also, considering I dont know the proper ecm service code for this truck.
 

· square body man
Joined
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218 Posts
Discussion Starter · #7 ·
Ill let you know if I need you shortly. I was having a few problems. Also, my work just got a modis scanner from snap-on, Im learning how to use it on my truck. I was having rough idle when cold, then high idle when warm. also, my timing would jump around while trying to time (10-20 degrees in either direction) I replaced the map because even with the vacuum line unhooked, i was still getting jumpy readings. That straightened up my timing problem. But today it acted up again, and I got a check engine light for low circuit or short in coolant temp circuit. So I hooked up the modis and low and behold i got 300* C in the motor (whats that like 600*F?) I just replaced the coolant temp sender in the front of the motor with a brand new GM one, so I know thats good. I actually cut the 2 wires going to the ECM and it still read 300*C. So i ran the service numbers on the ECM, low and behold its for a freekin trans am with a TPI 305. The idiot that worked on it before me replaced every single electrical part on the truck except for the bad one, sometimes replacing them with the wrong one (coolant temp sender and ECM) So Hopefully the junkyard is open tomorrow. HERES ONE FOR YA RIGHT NOW!!!! Can I use any ECM with a 2.5 manual for this truck? I was picking through a Fiero with a 2.5 in it. For the 1st time in 5 years the closest j-yard to me had no s-10s or blazers! Also, considering I dont know the proper ecm service code for this truck.


if the car is a 5 speed and so is your s-10, it should be compatible, but make sure to look at the ingnition coil on the pontiac fieros engine and make sure that it has a distributor and not 4 sperate coils, because that differance will not be compatible. the chevy 2.8 has the same computer though, i cross reference the part number at GM parts place and there is really no differance in the parameters nor part number. be careful not to get a 4.3 computer because that is the same as the chevy 5.7 ltr computer
 

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685 Posts
I just got back from the junkyard. I found a truck identical to mine in options except it had a 5 speed. I took the ecm and put it in mine, I am now getting ALL correct readings and the truck runs excellent.
 

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36 Posts
i cannot find the where to hook up the green wire. i cant find the symbol on coil either. i diagram would help very much. i have looked at the other posts but am still having problems
 

· square body man
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218 Posts
Discussion Starter · #10 ·
i cannot find the where to hook up the green wire. i cant find the symbol on coil either. i diagram would help very much. i have looked at the other posts but am still having problems
the green wire is the tempature cooling sending unit wire, or should be- which end are you looking at, at the computer end or the engine bay? i could be wrong, lemme read my manual and i will get back to you a little later, but it should be the temp gauge sensor wire
 

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im looking at engine bay. the plug that sends the wires to the distributor. negative one right?? there are two wires. im hooked into one of them. there is a plain black and a black one with a purple stripe.
 

· square body man
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218 Posts
Discussion Starter · #14 ·
im looking at engine bay. the plug that sends the wires to the distributor. negative one right?? there are two wires. im hooked into one of them. there is a plain black and a black one with a purple stripe.
plain black is ground and with the stipe should be positive, pretty sure about that, but ill check for sure
 

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i got all my wires hooked except for the green. my dad told me to hook it to the negative side of the coil. i found the negative side and spliced into one of the wires. nothing is working in thetach. only the light. i dont know what i did wrong. ive neverstalled them in a truck like this. only v8s
 

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just registered. iam looking to buy my first truck, and just waiting for a good s10 to come up on craigslist, i want one that has a good engine and thats about it, so i am coming to you for advice to tell me how these engines are, are they bullet proof or if not cared about break down easily. because its been a headache finding one with low kilometres/miles. and iam just wondering if a s10 with high miles have problem after problem.

i know if any engine is cared about they want last very long but generally how durable are these engines.

thanks
 

· Rarely goes over 20mph
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3,148 Posts
2.5l suck for power, if you just want good gas mileage from a 1st gen and dont care about speed power, or exhaust, go for it, otherwise get a 4.3l



on a sidenote, i just checked my fuel mileage, 14mpg CITY, driving like a grandma, not bogging the engine down or anything.

im hoping its just the weather, because i know theres a diffrence when driving the truck 5 blocks when its 10F out compared to 60F, but getting 14mpg city is worse than most v8!

so plugging in my old coolant temp sensor into the water neck, did nothing.
 

· square body man
Joined
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218 Posts
Discussion Starter · #19 ·
just registered. iam looking to buy my first truck, and just waiting for a good s10 to come up on craigslist, i want one that has a good engine and thats about it, so i am coming to you for advice to tell me how these engines are, are they bullet proof or if not cared about break down easily. because its been a headache finding one with low kilometres/miles. and iam just wondering if a s10 with high miles have problem after problem.

i know if any engine is cared about they want last very long but generally how durable are these engines.

thanks
the 2.5s are dependable, noisy little work horses, not hot rods. the will last a while if taken care of, which means some work, not as much as other models but they do need their share. every thing is fairly simple to work on, very basic if i may say, and repairs cost minimun, not many parts to change.
they are good engines, and gas savers.. just not hot rods
 

· square body man
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218 Posts
Discussion Starter · #20 ·
2.5l suck for power, if you just want good gas mileage from a 1st gen and dont care about speed power, or exhaust, go for it, otherwise get a 4.3l



on a sidenote, i just checked my fuel mileage, 14mpg CITY, driving like a grandma, not bogging the engine down or anything.

im hoping its just the weather, because i know theres a diffrence when driving the truck 5 blocks when its 10F out compared to 60F, but getting 14mpg city is worse than most v8!

so plugging in my old coolant temp sensor into the water neck, did nothing.
i know its odd, but have you checked your air filter or your injector?
 
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