formula90

O.K. first of all...thanks in advance to anyone who helps me. And I do need help. Guys, bear with me..this might be lengthy but Ido not want to leave anything out so you can get a good picture of what is going on. I bought my formula 4 months ago, and when I bought it, I bought with it a few problems.
#1 drivability---hesitation,stumble, on acceleration. either under small acceleration, or heavy acceleration. either cold,or warm. night or day..in other words..all the time. sometimes worse than others.
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#2 ecm codes 32 & 43----(EGR)(Knock-sensor/ESC)
I have installed new egr,egr solinoid, new knck sensor,harness,swapped PROM chip with known good chip. Good vacuum at egr, system is operational. can feel egr move when goosing throttle.
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#3 wierd noise----when I accelerate I can hear a clattering noise from the engine, then my check engine light comes on (code 43) then the noise goes away after the light comes on. (engine knock?)
O.K.? if you are still with me..thanks... now I will go over what I have checked so far....
Vaccum leaks,timing (6 degrees BTDC), fresh full tune-up (when I mean full i mean tps adjustment,fuel filters,air filter,cap,rotor,plugs,timing,pcv valve,etc...,all engine management sensors (all within spec using the Haynes Tech book),new o2 sensor,no carbon build up in egr port in intake mani.,and probably more if I can think of it!!!!
now after all of this I still get problems #1 ,#2, & #3!!
I am stumped...
Now for alittle bit of more info..
this car came stock with the 305 and before i bought it, it was fitted with the 350. and the guy i bought it from says it has behavedlike this ever since the engine swap. to my knowledge, the stock computer,chip,injectors(TBI) were carried over to this new engine.
is this where the problem is or is it maybe the fuel system. ie..bad FPR fuel pump..etc..or is it something mechanical wihin the motor..timing chain,cam, hell i dunno...dont know alot bout engine swaps...what can i check to get in the ballpark..
I have tried to lay this out simply...are the 3 symptoms the root of 1 problem, or what? I have tried to wait to see if someone else posted this problem, and so far only JIM I. has the same thing going on...please help me. Im pretty frustrated Thank you..



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Mike 25th

I'm no genius and probably have no business answering any of your questions, but my oppinion on problem #1...

...usually dead spots, hesitation, etc is cause by a faulty TPS sensor. You said you adjusted but did you make sure it was running between the right ohms?

It can get frustrating when you have a car that has already been heavily modified and problems were not corrected the first time around.

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92 Z28 - 5.7 - Black/Grey Leather
Macewen White Faced Guages
SLP T-RAM, 24lb/h Injectors
Accell 52mm Throttle Body
SLP 1 3/4" Headers and Cat Back Sys.

Macgyver

That kinda sounds like a timing problem, but have you considered loose rockers?

formula90

my timing is dead on guys and i checked my rockers aslso sounded good it is not that kinda sound. my tps is cool also. i really need some kinda feedback that doesnt include what i already painstakinly checked thoughrly already. thanks in advance..

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Kevin G

Do you have a scanner available. It sounds like detnation could be your problem. A scanner will show if the computer is pulling timing, and how many degees of knock you are experiencing.

You first unplugged the brown wire in the harness near the firewall when setting the timing right???

Apeiron

Maybe I'm being paranoid, but if it's not detonation, could this be the first signs of a bad rod bearing or something similar? This could cause clattering under load which would trip the knock sensor.

Hurtin4Hp

Is the knock sensor you are using for a 305 or 350?

formula90

good question i duno. could be a sensor from a 305. Rod bearing? hope not. check this out. i have a exhaust leak at my exhaust mani. at the firewall o the passenger side. do yall think the knock sensor is misinterpeting this vibration as spark knock? also YES i disconnected the brown esc wire to adjust timing. thanx for the help. alittle more insight would be greatly appreciated!

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Ski89Z28

I'm more familar with TPI systems And with them you need 22lbs injectors, is that the same with TBI units?
Also did the guy put a new cam in it? If so is it degree'd correctly? If it is out 4* your crank would be out 8*!?
Just putting in question to try to clarify.

formula90

my car is bone stock!!! no cam no nothin. the injectors are not the same as tpi. they are 42 punders not 22. anyways...thanks

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LDY

yeah I got super frustrated at my truck so much so that I sold it. It was a 72 chevy stepside and the engine was a rebuild that the guy hopped up. Eventually the thing blew on my. threw a rod cap threw the oil pan. I'd say it was a good combo of a thrown together engine and my teenage driving, but I had a terrible engine knock before this all happened. Not trying to scare you as I am not mechanically inclined either but check it out.

Good Luck