Truck falling on its face when in drive


#1

joedaddy

1 min ago

I have a 1994 chevy 350 tbi k1500 4×4,I’ve put plugs wires cap rotor,map sencer,egr,cooling temp sencer, injectors,pressure regulator,ignition coil,ignition control module, an I’ve done all the vacuum lines,timing,fule filter fule pump, thermostat,idel air sencer,starter, alternator, battery, an my truck still falls on it face when you put it in drive it gets worse as my truck warms up,some one help me out


#2

fuel injectors gone bad my guess,


#3

Just put them on last week


#4

New injectors? If so throttle body cleaning next guess, sorry I missed injectors in the post


#5

I’ve cleaned it out took it off an cleaned it


#6

Sounds like you’ve changed all the usual suspects and a few extras to boot. I think you need someone with diagnostic skills.

I’m gonna take a wild stab and suggest checking for (a) plugged cat converter(s), but I still think you need someone that can do diagnosis. Another wild guess possibility is a valve problem. That’ll take someone who can read and interpret a vacuum gage.


#7

It’s got a straight pipe flowmaster with no Cadillac converter


#8

No codes come up no check engine light


#9

Since it does not have a Cadillac convertor it will stay a Chevy.


#10

Your '94 has an OBDI system, so you won’t get the same level of help from it as the OBDII systems would give you.

If the flowmaster has replaced the catalytic converter, the upstream O2 sensor may not be sending correct readings to the ECU… and… was it removed along with the cat converter? Did you just make this change, or just buy the vehicle this way?

Just as an FYI, it’s called a “catalytic converter” (“cat converter” for short), because it uses a catalyst to reduce unwanted emissions. A “catalyst” is, by definition, a material that causes a change without itself changing. In the case of the cat converter, it makes changes to the chemistry of the exhaust stream, but does not itself change.


#11

I bought it with the flow on it so I have no idea


#12

how does the timing check out?


#13

It’s timed right I took it to a shop it idols at a 1000 rpms an runs at 600 rpms


#14

Did you just buy it?
I’m developing a theory that the previous owner removed the cat converters (perhaps even the oxygen sensors) and replaced them with the flow through mufflers, couldn’t get it to run right, and sold it to you to deal with.

The O2 sensors provide crucial information to help the ECU adjust the amount of fuel being delivered to the engine.


#15

Iv had it a lil over a year,it hasn’t had power like the power it has now after all the new parts,if it would just run right an not fall on its face, there’s no o2 but there is 1 sencer on my pipe idk what it is its befor the flow


#16

If it has lost a lot of power just recently, given everything you’ve already done, and presuming yo’ve checked for stored OBD I codes, first thing I’d do is remove the entire intake air assembly and make absolutely sure that’s a clear path, it’s intact, no rips or tears, no leaks, and no mice or bird nests, etc.

Next up, fuel pressure test.

If all that’s ok, after that would be some combination of compression and leak down tests.


#17

Just did the fule pressure test it was at 13,so it’s not that


#18

Please don’t listen to me but you replaced the cooling temp sensor, but the engine temp sensor is what tells the computer the engine temp and sets the fuel ratio (I think or in conjunction). Also what about the MAF? Could it be leaned way out but not enough to set a code? Agree, before more parts, prolly pay $100 to get a diagnostic computer on it. Then you can see if its too rich or lean and if the sensors are working.


#19

Ya I’m open to doung anything


#20

Are you certain 13 is correct for the fuel pressure? Most modern fuel injected vehicles would be in the 40-60 range. I’m not saying 13 is incorrect, but its unusual for port fuel injection anyway. Maybe that’s correct for throttle body though.