1987 TBI Misfiring

[rys272]

Ok so this all starts if my memory is correct after I changed my water pump and as I was doing that I was like gonna take this air/smog pump off might as well, if I remember correctly it never misfired before that.

Now the misfiring is absolutely random it’s not consistent it happens in park idling, neutral, driving, it’s consistent in a way that when you hit the gas it starts to misfire a solid amount. so is timing not advancing?

I’ve fixed any broken vacuum lines and have purposely plugged off any that haven’t made a difference because it still misfires.


Rebuilt entire throttlebody down to new screws and cleaned the **** out of it new injectors too they spray/mist perfect

Started with the basics -
Cap
Rotor
Wires
Plugs
Fuel filter

Paper cliped the obd1 32 and 33 came up so I took that vacuum line off the EGR and plugged it, unhooked battery for 30min to let those codes **** off.

Anyone have a similar problem before because my next step is dumping more money

all the last things I can think of -
IAC
Map
TPS
Check every ground over (again)
o2 sensor
Check plugs & wires (again)

Random thing I should mention exhaust is cut off because if i didn’t cut it off it would probably fall off while driving it was that ****** but other than that only big modification I’ve done (No I didn’t cut out part of manifold o2 sensor is still intact and everything)

 

[Vbb199]

HAve you replaced the EGR? It has a rubber diaphragm in it that can crack/break and leak

Or, there might be a carbon deposit in the pintle. Check that.

Use a mighty vac on the egr, see if it pulls a vacuum.



Code 33... the map

It needs that to be in working order to deliver fuel properly.

TEst it, or replace it

 

[fast 99]

Check for steady vacuum then compression after EGR as suggested.

Most times the pintle in EGR can be raised with a finger. If no change EGR is leaking.

Uneven vacuum suggests an internal engine malfunction.

 

[rys272]

Update, Success kinda? Replaced MAP, cleaned out tps plugin, cleaned some grounds up, Didn’t work had new codes popping up and still misfiring. So it started to get dark out and I was still ****** around with it unplugging tps map etc and all of a sudden I see #5 spark plug arcing like a ************ so I grab one of those old spark plugs what do ya know runs ****** amazing anyways so I’m driving her around for a hour and a half stop home real quick jump back in her take off and half way down the street all of a sudden a horrible bog/misfire like it’s running on two cylinders almost about to blowup so I absolutely limp it home won’t go faster than 5 kmph so yet again I’m stumped did I burn a valve or what gonna pull all plugs tommorow and check them all but really hoping it’s that #5 or some codes popped up.

 

[rys272]

Been messing around with her this morning right injector good spray working good, left injector absolutely zero spray and then drips once the truck dies, Guessing I got sold a ****** injector?

 

[Vbb199]

How about the egr

 

[rys272]

How about the egr

Egr is fine, did get sold a bad injector put old injector in left side thing runs brand new again. Moral of story as usual check ur plugs wires and fuel before ******* around with sensors and ****.