Still Runs Poorly... ??

[jmgtp]

I'm familiar with the knock sensor. I know what it looks like and where it is, although I have never had one go bad before so never had the pleasure of replacing one. Ya there is a bunch of wires up by the plenum, those would be the ones that got josseled a bit as I wrenched my hand down to the depths to retrieve the plugs/wires. I'm going now to change the front motor mount and do a visual check of the knock sensor wire and maybe unbolt the exhaust at the downpipe and see what happens.

thanks for the input and please keep it coming! I'll do another update after I replace the mount / check the KS and undo the exhaust and run the car to see what happens.

[jmgtp]

UPDATE

changed the front mount. It was a pain to line back up. That mount looks like a terrible design, the rubber holds to the metal centerpiece at 4 weak places where the rubber is thin. The mount that I took out had 3 of the 4 broken, leaving I'd say less than 1 square inch of contact, no wonder the engine was hoppin all over the place. Took a look at the KS, it looks ok, plugged in etc, and out of harms way (harm being my grabby hands when i changed the plugs :P ) Didnt unbolt the downpipe because all the penetrating oil in the world wouldnt help those nuts loosen and I was scared I would round them. The cat passes the fist thumping test (read: no rattling). The heat shield was rusted badly and rattling and was removed and the rattle gone, plus I still cant imagine the cat going bad over a period of 20 mins when the engine wasnt even running! hehe. Damn I NEED a scan tool. But until I get my hands on one... if you have any other ideas please lemme know!

thanks everyone!

-john

one last thing... with the front end in the air, and the car in reverse (manual trans) if I spin one wheel there is some pretty heavy resistance (seems like more than the 284 in my grand prix has if I do the same thing - in the air in R). Doing this in R means the differential does its thing and the other wheel spins opposite. Doing this in neutral, the wheel is very easy to turn, however the opposite wheel remains still and the trans spins. Wondering why in gear there was so much resistance (especially in comparison to the same test with my 284 which has beefier guts to turn so in theory should be the more difficult of the 2) ?? sorry this got long![/b]

[Anonymous]

Just take it to the dealer and have them hook up the Tech1, you cheap bastard!!! Too bad you dont live by me, my friends dad is the service manager at a dealer here.

[jmgtp]

Just take it to the dealer and have them hook up the Tech1, you cheap bastard!!! Too bad you dont live by me, my friends dad is the service manager at a dealer here.

Dealer!?! Hell no! I'll burn the car to the ground before I take it to a dealer. Who in their right mind would pay $70 for them to plug a computer into the aldl and scan it taking all of 3 minutes.

[Anonymous]

Just be like: "Lemme go get my check book from the car..."
*vroom* Gone.

[jmgtp]

Took it for a spin. The new motor mount cured most of the violent bucking (still bucks some cuz the engine runs like crap). The ecm has code 33 for map sensor stored. The sensor is good (pulled it off my running dohc) and the harness has 5 volts on one lead ground on the other and the remaining lead is the signal lead so it has no voltage reading when the harness is unplugged. The code may just be stored from last week when I started the car with the map sensor unplugged to see if there was any change for better or worse in how the car ran. So bottom line is the car still doesnt run right, and is making so little power that I couldnt get it to a shop to have it checked out if I wanted to.

I need this thing to work

[v6h.o.]

i work at a dealer......

usually sometimes we just scan check a code for free for some customers if they just need to know "if its something thats going to leave them on the side of the road"

i always hear nothing but horror stories about american GM dealerships...

[jmgtp]

I can check the ecm for codes without a problem with the old paperclip trick. What I really need is to see the data that the ecm is seeing from the various inputs so I can get some insight on why the car is running so poorly. My aldl=>laptop cable doesnt wanna work right so I'm outta luck with using freescan to read the data.

[jmgtp]

I just checked the wiring for the knock sensor. I removed the clip from the KS and using a digital multi meter first checked for a short to ground. There is no short to ground. I then turned the ignition on and measured voltage. 5 volts on the wire. No SES. I am so clueless on whats wrong with this thing. It still has no power and surges a bit and as the engine warms up things get worse. Seems to start/idle/rev in nuetral just fine though. Lacks so much power that it is not driveable.

thank you all for your continuing advice. Please keep it coming

-john

[Anonymous]

Check the thread I posted in the computer tuning area of the forums. There is a link to an ALDL cable for $50 shipped and its of high quality I hear. I think Im gonna get one, but I may be spending $2500 today.

[gpse3400]

If I were you I'd pull the spark plugs and start from there. See which ones look good and which looks bad. Bad would be black, or severly white. You might've got a bad wire. Sometimes parts , though new can fault. If this happened after you changed the plug wires then I'd go there. Like I said look at the spark plugs you should find the answer there.

[GPXSS]

if any new parts were bad, id say it would be one of the coils. Check the resistance across the poles. Bad thing is that lots of electrical things with coils in them can act fine when cold, but screw up when hot.

The only other sensor I can suggest would be the TPS.. i know first hand that when those go bad, or if there is an intermittent connection on one.. your car will totally flip out and surge like the MAP sensor just took a dump.

You can use the DOHC injectors to test, but id suggest rather find some 3.1 or 3100 injectors from someone or off ebay to try.. that way, if they work you can just leave them in and not do double the work to pull them back out.

[bwawuz02]

wouldn't you think that if it was running fine in neutral that maybe it's the tranny you need to be looking at? if not, i'd say change the Cat, KS, TPS, and put the original MAP back in.

[jmgtp]

ok to adress the responses in no particular order...

TPS seems good (measured its output signal with a meter and ~4volts at WOT and something less than 1V at closed throttle)

I've gone through 3 different sets of wires to be sure, they cant all be bad

Plugs all look the same

Trans was fine 5 mins before I pulled the plugs so I dont see how it coulda gone bad when it wasnt even running, not much to go wrong with the 282 anyways

Cat could be bad, but like the trans, whats the likelyhood that it goes bad over the timespan that it took me to change the plugs with the engine not even running, plus no foul smells or rattles (if I shake it)

Had 3 different Ignition control modules (all with their own coils) through this thing, the one in there right now is the one that came off my perfectly running dohc so I know ICM and coils must be good

yargh! I hate this thing!

[Scott_68B]

John,
Has to be something that was disturbed when you changed the plugs. I assume that you checked to make sure any wiring in the area you were working is not broken or was not accidently strained during the plug change or that anything you unplugged is secure now. Are you sure the plug wires are in the correct order?
Scott