84GN about to get the boot

turbo84gn

I'd rather be waterskiing
Okay guys, I give up. I am really frustrated. I can't even get the darn thing to idle. Here is a turbolink file of the 20 seconds I could get it to run. (right click on link and select 'save as') http://www.skiboathelp.com/art_84gn.ecm Maybe someone can see something I missed. The car is a completely stock 84 GN, It started running like crap all of the sudden one day when I went to go move it. The car is currently undergoing an interior restoration, so lately it only gets started about every other week. I checked the plugs, four were fouled. I replaced the plugs and wires, and they fouled again, car wouldn't run. I checked fuel pressure, steady at 30lbs static. I did a leak down test, lost only 2lbs after four hours. I replaced the coil pack and plugs, again same results. I then upgraded to the 87 CCCI module (the 84 was too pricey), replaced plugs, same results again. I then installed a known good set of used injectors, replaced plugs (parts guy is starting to wonder where all those plugs are going!). Same results, won't run and plugs fouled or wet. Other things that have been replaced recently: O2 sensor, MAF hose, all vacuum hoses, PCV, fuel filter. Any suggestions on what to try next are GREATLY welcome! Preferably, before I drag the car with the tractor out to the back fourty into the weeds.
 
I couldn't see much from the file when I looked over it. Its hard to see whats going on without it warmed up. Does the car run the same with the MAF unplugged? If anyone has a 84/5 try and swap out the MAF or the ECM to see if that helps. You think maybe the cam/crank sensor could be off/bad?
 
Will it run with the MAF unplugged? What should the car run like like that (assuming it's the only problem)?

Also, didn't think of the crank sensor. Is it the same setup as the 87GN?
 
If the MAF is bad then it will run better than it does now when you unplug it (but still not like it should).

The crank and cam sensors is the same setup as the 86/7 but they might be a different part number.
 
Also your T-link file looks like it is in ALDL not road mode. Does your car always idle that low?
 
I had it in ALDL mode to capture more data (you don't get much from an 84 in road mode). And no, when it was running right (eons ago now), it didn't idle that low. I'll check the other stuff tonight. Thanks.
 
Art...can't read the file 'cause I have no scanner.

Any codes ? SES light ?

Here's some things I messed with during my long no start situation and shortly thereafter.
First u said it ran like crap for a few secs then u finished off sayin' it "won't run"....does it start at all and won't idle or ?

Here's what I did on mine:

Cleaned all gnds under the hood - ones on fenders (both), firewall and motor - also chk and renew gnd on the module / coilpack bracket to engine.
Cleaned and flow tested my injectors !!!!!
Replaced 2 cam sensors
Get #1 cyl at "0" TDC and check voltage on "B" wire at "0" TDC thru to 25 deg. after TDC...see if it changes or shows erractic voltage (ie. 10-15 volts) with no change when it hits 25 deg after TDC (mine had high voltage and no change on full rotations of cam sensor = bad) Should be about 7 v then zero when u hit 25 deg.
Got spark ?
Set IAC (if you can get it to run of course)
Set TPS volts
Check and set if necessary the idle screw on rear of TB

....and i'm assuming u've got lots of gas right ?

My car won't run with MAF unplugged...don't know why...will yours ?
 
No codes, no SES light (yes it works, it lights when you first turn the key, and the only code I get is 12).

Unplugging the MAF made no difference, still wouldn't run.
I have spark (at least the timing light I have says I do), TPS has been set.

If I let it sit for an hour it 'may' start and run for a few seconds, or just sound like it wants to. Then it won't start at all. I'm assuming that the plugs are getting wet and not firing.

My Dad suggested that maybe due to the mileage on the car, and the fact that the motor is still untouched, that maybe it jumped time and needs a new timing chain. The previous owner never fixed a broken speedometer cable, but I'm guessing mileage in the 70,000+ range (odometer reads 53,000). I think I might pull the front cover off and check (and replace it while I'm at it...).

I'll also check those things you mentioned HOTSIX.
 
Timing Chain? wouldn't rule it out, but they are usually good for 100k+


Have you tried an ECM? That fixed Twins' ride.....it would run perfect for 2-5 secs. and then die. If I still had a spare I'd come help ya out.
 
84-85 and 86-87 crank sensors are different. One has a long female plug and one has a male.

Car has gas in it, right? Do you have enough fuel pressure? If you don't have a guage, you can push on the shreider valve on the rail while it's running and it should squirt out under a lot of pressure. The sock in the tank could've collapsed or fuel filter is plugged. How long did it sit? Bad gas maybe?

Before you pull the front cover, pull the fuel pump block off plate on the side of the cover. If the chain is loose enough to jump time then you will be able to move it a lot with your finger.
 
Just thought of this!

Could be the cam sensor is set "late"...when I changed my timing chain/gears, I ended up with mine set "early". It ran, and actualy fairly decently, but the timing was so advanced that it was real hard to start, especially when hot. The reason I say "late", is when I figured out my problem, I did a little experimenting while the cam sensor was loose. It was REAL apparant when it was set correct, setting it "early" made it hard to start like it had been, BUT setting it "late" made it almost impossible to start. It actually only started once, but just died.

It's possible the cam itself is out of whack, but because these engines have the tensioner, about the only way it'll jump time is if at least 2/3 of the teeth on the cam gear are gone!
 
I like the way cool84 and BFH are thinking...

My thoughts are the same....

CAM SENSOR (broke / not set)

FUEL (Pressure / Empty / Wet plugs)

and lastly INJECTORS !

The story on mine was that they were cleaned and flow tested 2 mos before I put the engine back together. If the shop that cleaned them does not put a drop of oil in them afterwards they WILL sieze up if they sit for any length of time not lubricated (fuel or otherwise). My shop initially did not 'cause they thought the injectors were going back in the car right away. Cost me a second cleaning and much hassle on the no start diagnosis.

MAYBE your injectors did not have gas in them if it was not started for awhile and they siezed. I was getting a very small amount of gas (I mean very small) on my plugs, causing me to think it was getting gas when it was not. Make sure those plugs are soaking wet.

Spark + Compression + Fuel = must fire.
 
I will check the cam and crank sensors tonight.

The injectors are good, they just came off my Dad's 87 (he upgraded to 42lb injectors), and are known good. Fuel pressure stays at 30lbs static, even after key is off for several hours, Checked ECM connection, looks okay, I don't see any corrosion.

I'll see what tonights inspection reveals.............

Thanks for all the great tips! I really apreciate it!
 
Okay, I checked the CAM sensor B terminal, stayed at 5.04v, regardless of crank position, never changed. I disconnected the sensor, and checked the voltages at the connector leading to the ignition module, I had the following, A=12.4V, B=5.04V, C=0.03V.

Can I assume there's something wrong with the wiring? I double checked my 84/85-to-86/87 conversion wiring, it's right ( I converted AFTER I was getting the no-run problem, to eliminate a bad module). Should there be 5V or 0V there:confused: Or should I just assume a bad cam sensor and replace it?

At least I should be able to return the timing chain without breaking the seal.

At least I've narrowed it down and ain't guessing now! Thanks a lot to all who helped! :)

Only question now, is it cam sensor, or wiring?
 
CAM SENSOR

"B" wire must go to zero when the interruptor passes thru it. Check the resistance on the sensor just to be sure...but I almost guarantee you that will get you the same result and the sensor is toast.

Install a new one (following the directions - of course) and I bet she starts.

Note: I got mine (twice) from a UAP / NAPA dealer...it was like 60 bucks CDN...which I think is like.....free in USD!!! Way cheaper then the GM part...

Let us know what happens.
 
UPDATE #2:

I have removed the cam sensor. I took it in to my workshop, applied 12V+ to A, and '-' to C. I read 0v at B, regardless of position. I removed the top, but the "revolving cup window" was still in place. So, a new cam sensor is on order for $44. None of the local parts stores had one in stock. Not sure of the brand, but the local chain (Ridge & Kramer) only uses name brand stuff, so I know they're good. As a side note, AutoZone wanted $109.99 for it!

I should have it by Wednesday. Thanks for the help guys!:)
 
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