420A Won't Start

[tcavenger99]

OK here is the story last year when i put my car away i sprayed it on the motor with rust check(dumb). it was started all winter long and was in cold storage. when i finally went out to start work on it it started yet wouldn't idle correctly. when i turned it off it wouldn't start again . A few weeks passed and i went back out to were it was stored with all the parts i thought would cause it not to run ( crank sensor ,map sensor voltage tester , water remover for gas the only thing i haven't try ed are cam and ecu) . So before i started ripping things apart i tried to start again and it started first key turn PERFECT right wrong.
It wouldn't hold at idle it would run fine for about 5 min then only if i gave it gas would it keep going. If it died i could turn the key off and on again and same thing idle for 5 min then die. At first i thought it must be rust check on the idle air control valve or something. So i proceeded to leave the engine now that it was at least starting and go work on installing inner cooler. About 2 weeks passed and i was going out again to see if i could fix the idle issue and take it home . When i try ed to start it once again same prob no start crank and crank no start . so with that i first started to see if there were any codes and only code 12 bat disconnected came up ,then i cycled the engine again with the coolant sensor unplugged to see if the ecu was reading sensors and it was. plugged sensor back in and then replaced crank sensor. still no start checked for spark very little ,fuel pressure is OK 30 psi regulated by sfmu. Then tested asd relay that was OK. checked for bad gas no thats fine trust me .crank sensor shows voltage going to it and new coil on it so that cancels that to. Proceeded to ecu checking continuity all pins seemed fine but pin 52 which i think is ecu ground there is nothing (were is it grounded) . Then puled harness no broken wires . this is driving me nuts . So in short will a shot ecu still set codes ,if i have no codes could it be cam sensor , Does anyone have anything else that i can try please .

just to sum up what this is its a 420a turbo 8.1 positions with a warlabrow 255 fuel pump and the egr is blocked off and there are no vacuum leaks.
and just for anyone that asks i have looked all over the fourm and googled all this already

 

[tcavenger99]

and timing is OK

 

[tcavenger99]

this is the ecu pins

 

[tcavenger99]

pin 52 at bottom

 

[rush2252]

Bad CAM sensor? If your getting weak spark and youve tested the CPS then sounds like it could be the CAM sensor. Also this can cause a 420 to have poor idling etc.


Kolby

 

[tcavenger99]

but i thought that a 95 420a would start without a cam sensor ?

 

[rush2252]

I think its the 2gb's that will start without them. My 99gs would but my friends 95 avenger wouldnt. I assumed the same thing after owning the newer 99 with the updated plug style. So I scratched my head for about a week and finally figured assuming makes and Ass out of U and ME.



Check the Cam Sensor
Kolby

 

[tcavenger99]

getting cam sensor will try this weekend tell u how it turns out anything elas i can take with me to try

 

[VelocitàPaola]

getting cam sensor will try this weekend tell u how it turns out anything elas i can take with me to try

I don't think your symptoms are consistent with a bad CPS. Even if the CPS were completely disconnected, the car should still start (albeit after a bit of cranking) and run just fine.

If the application of this "rust check" stuff is the only thing that changed between now and when your car was last running, I would keep doing what you're doing: look for areas where this stuff could've gotten and caused damage. Specifically, sensors and connectors are the most vulnerable. I would also look at the spark plug wells.

 

[rush2252]

I don't think your symptoms are consistent with a bad CPS. Even if the CPS were completely disconnected, the car should still start (albeit after a bit of cranking) and run just fine.

If the application of this "rust check" stuff is the only thing that changed between now and when your car was last running, I would keep doing what you're doing: look for areas where this stuff could've gotten and caused damage. Specifically, sensors and connectors are the most vulnerable. I would also look at the spark plug wells.

Have you check the main harness connector on the back of the motor? It should have 8-10 wires approx it disconnects the crank sensor knock sensor and oil pressure switch harness from the main harness. It should be near the throttle body of under the intake.


Good Luck
Kolby

 

[tcavenger99]

i took the harness apart and checked couldnt find any breaks or dirty connections . were there are no codes it has me baffled ........ just found a 98 neon with a 420a in it for $25 taking that home thursday and scraping it . cheaper than buying a bunck of sensors .the weird thing is that when the battery starts to die it almost starts ????

 

[rush2252]

Why do I get the feeling this is another "oh yeh I forgot to mention some pertinent information" thread?

Something has to be missing. Any chance a rodent did some chewing on anything? If youve replaced everything in the ignition system I cant give any more suggestions. You didnt do like a waterpump swap or mess with the timing before you parked it? In the post it says you started it off and on all winter while in storage and then whenever you went to pull it out it started and then died. Now it wants to start but doesnt?

Do you have spark? Im guessing a faulty fuel pump. Thats the only info you havent given. If its got the correct fuel rail with the FPR you should be able to tap a gauge with the schraeder valve fitting and check pressure at the rail. I believe N/T stock are 44-48psi somebody correct me been awhile since the N/T days


Good Luck
Kolby

 

[tcavenger99]

yes but i have the fuel pressure set at 30 with my sfmu

 

[rush2252]

well for starters your factory fuel pressure setting is 46-49psi. A stock car wouldnt run on 30psi. Yours is modified however.

Go back to basics. Do you have spark? Are your injectors pulsing? Do you have compression? If you have spark compression and are getting fuel to the rail bump up the fuel pressure to 45 and see if it will start. Then mess with tuning. 30psi sounds really low for the N/T cars even running the turbo setup


Have you made sure the battery has a charge? The fact you have weak spark is sticking in my head. And you havent clarified but is it still no crank no start? Or just crank no start?

Let Me Know
Kolby

 

[tcavenger99]

OK i am running 36lb injectors and they are regulated at 30 psi with sfmu. i have fuel spark and all the good stuff yet spark week. the car didn't start then after being left for a week went back out and it did start and hasn't started since . all it does is turn over and over again . yet the weird thing is once the battery goes down it almost starts and the tac gage flutters (telling me the crank sensor is picking up single ) yet still doesn't start? when it did start last it would run for 5 min then die. I am not a newbie to electrical nor a stranger to automotive . i have also taken this problem to some of the best guys in the field . yet they two are stumped. and to make matters even funner one of my buddies is having the same problem with a 98 neon and it has bin in his garage for about a week and he has replaced everything. and just to add its not the asd relay

 

[rush2252]

There are only a few things that can cause weak spark. Bad ground, faulty crank sensor, weak coil, dead battery, possibly ECU issues.


The fact that you sprayed the Rust preventative could either be the issue or just another coincidence. I dont think spraying down the engine bay with a product would have such effects on the cars ability to start but I could be wrong.

Have you tried ohmING the harness from the Crank sensor to the LARGE connector on the back of the block to make sure your not getting a large amount of resistance? Another way to check the crank sensor is plug a logger in and the tach reading should be moving on the logger while cranking.


Just for the hell of it have you changed the plugs through all of this?


Good Luck
Kolby

 

[tcavenger99]

OK after rewiring the whole car (good god) testes all sensors and checking grounds the dam thing still wouldn't start. so after banning my head a few times i decided to pull the plugs again and swap them out for some old ones i had in my box. O my god it started WTF so i let it run it ran for 5 min then dropped idle again and stalled ? So now that it was running i thought that maby one of the sensors was clogged with the rust check so i put some intake cleaner in and a hell of a lot of black smoke emerged . ran it for a little wile longer and then hooked a fuel pressure gouge up it read 30psi i tightened the screw on the sfmu with no raise in pressure ? yet loaded it up holding brake and pushing gas .turbo spooled to 10 psi and i saw the gouge go to 98psi with Afr reading 10.12 and steady. still lots of black smoke though . now that it is running kind of (still sputters under idle ). i returned home so any insight the plugs i had in it were bkr7exis what should i bring back with me next time . plus any other ideas on y she wont hold a steady idle?

 

[rush2252]

I wouldnt run Iridiums stick with the BPR7ES. It sounds like your AFPR is jacked. You said it climbed to 98psi??? Wow.. Back the screw out. It sounds like the base setting on the thing is 30psi if your seeing that much fuel your getting cylinder wash and thats why the car isnt running. This would also explain the black smoke as well.

You said AFRs were 10:12?? It honestly sounds like the diaphragm went bad within the regulator. If your seeing 10:12 With 98 psi? Something definately isnt making sense or Im misreading your previous post


Kolby

 

[96TurboGS]

Rush: remember what forum section your in, high fuel pressures with 36lb injectors sfmu/fmu on (420a's) 1bar map sensors are common. However, I agree with keeping the BKR7E's (NOT BPR's). OP: What ratio disk/spring are you running those injectors?? Free rev at a standstill isn't going to tell you much (being the VE need is different under load). What's your idle AFR?

 

[tcavenger99]

afr under load ( foot on break and gasing) as far as disk size i am using the big one that was included with the vortec sfmu

 

[rush2252]

Rush: remember what forum section your in, high fuel pressures with 36lb injectors sfmu/fmu on (420a's) 1bar map sensors are common. However, I agree with keeping the BKR7E's (NOT BPR's). OP: What ratio disk/spring are you running those injectors?? Free rev at a standstill isn't going to tell you much (being the VE need is different under load). What's your idle AFR?

I know what forum im in.. keep in mind we are talking about gasoline engines not diesels. 98psi still seems crazy high to me even on an N/T

He was getting weak spark most likely from fouled plugs from too much fuel which overtime would cause cylinder wash. Hes also running the stock ignition or no?

 

[tcavenger99]

no i am running 36lb acell injectors .

 

[tcavenger99]

ok car starts yet lots of black smoke idle fuel preasure is 30psi with 36lb injectors when gets warm the black smoke comes out .if u drive it driving normal is fine yet as soon as i see boost black smoke . the vortec sfmu has the big disk in it and the big spring

 

[talon740]

NO NO NO NO....check your asd relay, it sits next to your fuel pump relay...the asd powers everything, gives you spark to coil, plugs, wires, the whole nine, believe me, even though you look at it, it may look ok, but the asd can burn up underneath, so take it out off the plastic piece, before you end up spending more than about $400 on all new parts like i did, even a new ecu, yea bummer!!

 

[talon740]

ok nvm mustve skipped your previous post, wires eh? for some reason i was thinking that you wasnt getting spark to anything, great it runs now!