I recentley rebuilt the engine and i noticed i now get 16L/100 Km on an88 camar 2.8 v6
which is really allot, and also after i rev it to around 4000 and sharply drop the accelerator it backfires a bit which led me to believe it runs too rich is this the case , or do i have another problem ?
also when i use engine braking for a long time , lets say about 2 km in 3rd and sharply brake , the engine sometimes stalls.
what coud be the problem (its a 5 spd. manual.)

thanks

 

can anyone please help ?

 

Is it stock exhaust?
Carb or fuel?
is it backfiring through the carb? If you have one?

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Chevy 2.8L 60° V6
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http://www.geocities.com/fiream/RobsCarArtPa.html?994187591828

 

its a mpfi 2.8 v6 stock exhaust (to the best of my knowladge)
and its not a really loud backfire i hear coming from the exhaust, last night i checked and the plugs were also wet, and i think that means the mixture is too rich , but how can i adjust it. could it be the 02 sensor?

 

I would check the codes but I would be willing to bet it's the O2 sensor. Does it rev high at first start up then go down? or does it stay high all the time. If it stay high all the time your should have a code somewhere. If it goes down after a few minutes it's probly the Oxy.

 

Make sure the plugs are the correct heat range and gap. If a plug doesn't reach it's self-cleaning temp, it will foul, and won't produce a strong spark. You could also check timing; a misfiring engine can also cause a wet plug. Make sure the contacts inside the cap & rotor are free of carbon deposits.

Check too for a dirty air filter. A dirty air filter = less oxygen = runs rich. Along those lines, make sure the throttle body is cleaned out, and make sure to clean the IAC valve/passageway in the TB (see my message to OneTireFire). Also, check the TPS adjustment- if it's higher than it should be, you'll be richening the mix (computer expects more air than it's getting).

Also if you've never changed the oxy sensor, change it anyway!

Just curious: How did your rebuild go? What kind of pistons & rings did you use? Did you have any machine work done (hot-tank, magnaflux, bore, hone)? Did you re-use the rod bolts or did you buy new? What about the bolts for the main saddles? Thanks!


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-Tom P (Hot rodded 1986 Firebird 2.8l)

 

thanks for the replies, my rebuilt went just fine (took me 4 month) but thats ok.
ive installed a new crakshaft+bearings cuz the old ones were so bad, i couldent even get the crank macined,it was that deep.
installed a new cam+rollers etc.
pistons, rings, oil pump, water pump, had it rebored (if thats how you say that),replaced the flywheel+clutch,and as for the heads and intake manifold, ive done nothing but having them cleaned, then ive replaced the fuel pump
filtersand that kind of stuff, the compression im getting now is 160-165 psi,
now im thinking of replacing the fuel pump and maybe the surges,and stalling problems will go away . btw ive replaced the PCV valve + air filter + adjusted the timing and now its no loger running too rich.... wooho.... , then im planing on doing some cosmetics to the car ,although it looks good as it is ......
Love these 3rd gens..... especially 87-91

so, does any1 know why i get surges in second gear (sometimes a bit in third but really rearly), and stalling after a prolonged engine braking.

thanks for all who viewed , and read it all.

 

Could be leaking injectors or fuel pressure regulator. Hook up a fuel pressure gauge and turn the key on. Your pressure should rise to around 42-45 psi and HOLD. If the pressure begins to bleed off then you have a fuel problem.


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-Dan
-1990 3.1L RS
-Mods? no
-Slow? yes
-Currently collecting parts for T5 swap

 

i thought it was supposed to blled of after some time , is it true , if yes then after how long ..
thnx for the replies

 

If it bleeds off within 20 minutes then there is a problem. The car is designed to hold rest pressure so the fuel does not boil but it will eventually bleed off. Normally it should hold for a few hours.

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-Dan
-1990 3.1L RS
-Mods? no
-Slow? yes
-*Slowly* collecting parts for T5 swap

 

thnx allot man
i really appreciate all u ppl helping the dumb rest of us
lol
thnx

 

Cool, thanks for the info! How much were all the parts, do you remember? Also, did you put the engine together yourself, or did the machine shop do it? Did you use a high-pressure or high-flow oil pump, or stock? I was thinking about using a stock oil pump with GM's high-pressure spring. Thanks too for the compression info; 5 out of 6 of my cylinders have that compression. Er, well, they had that compression 2 years ago...

The surging might be a vacuum leak; some of those old & brittle hard plastic vacuum lines might've cracked during the engine swap. You can repair cracks with pieces of regular rubber vacuum hose, or you could replace all the plastic lines with new hose.

The surging might also be a leak in the air intake tubes.


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-Tom P (Hot rodded 1986 Firebird 2.8l)

 

actually i used stock GM replacement oil pump, and thnx for the info for what the surging might be caused by
i'll check vacum hoses