86 Carrera Problems - Page 3

widgeon13 · 09-06-2009, 10:04 AM

Got the battery to 12.4 volts and no start, fogged the ICV and no start, jumped the fuse for fuel pump and cranked engine, no start. Checked voltage to the coil and that was OK. Not sure what to do next other than see if I have spark at the plugs.

kidrock · 10:38 AM

I'm no expert for sure, but I've read here a few times that the voltage you've registered may not be enough for your systems to operate properly, resulting in a "no-start" condition. Although I don't believe this to be your problem, I could be wrong.

Just to be safe, and since you've been running back and forth, go ahead and put a trickle charger on your batt and wait until fully charged. Then you can safely move forward with your diagnostics.

************************************************** **********************************

OK, I see that you've already done the necessary stuff to your battery. Sorry, I was a bit late with this last post.

Before we check for spark at your plugs and wires, remove your distributor cap and take a good, hard look at the condition of your cap inside and out. If there are no cracks at the connectors or on the inside, spray some WD-40 on the inside of the cap and wipe *CLEAN*. Are the connectors clean, where the wires connect to the outside of the cap? Clean those up as well. Take a look at the rotor. Is it cracked? If just a little dirty or corroded on the tip, clean it up. Put it all together and give it a try again. If no start, we'll move to the wires / plugs.

Almost there.........hang in there, dude.

ischmitz · ischmitz's Garage

Your voltage is fine. If the car tunes over there is enough power for the DME to run. If you haven't done this try these things:

Switch the ignition to ON. Then feel the ICV. It needs to vibrate and shudder with a 1 second interval. If that is the case your DME is alive and powered. If not you have an issue with your ignition switch/DME relay, wiring or a bad DME.

Next, have an assistant and check for spark. The easiest is to have an extra spark plug and pull one of the plug wires. Connect it to the extra spark plug, ground it to the engine (metal) and then have the assistant crank. You need to see sparks. Be carefull and use a glove or isolated pliers. While not life-threatening a spark can give you a little jolt.

If you have spark you confirm that your DME is getting the speed signal fine and has most parts working. Also you should at this point smell the tail pipe. You should be able to smell fuel. A more elegant way to test for spark is to have a timing light with magnetic pickup. A good excuse to head to the local auto parts store.

Then test the fuel pump: While an assistant cranks measure the voltage on fuse (3) fuel pump. You need to see +12 volts during cranking. You might want to get an LED test light and check for fuel pulses directly while an assistant cranks. Disconnect one injector and measure.

I believe the jumpering of various parts is not really going to help you here at this point. You already replaced the one part that can be bypassed: The DME relay. Now it is either a bad sensor (speed or reference or both) or something wrong with the DME.

In most cases it is one of the sensors and you won't get spark or fuel. Sometimes you get fuel but not spart at the proper timing pointing to the reference sensor. And if both are fine the DME itself can have a bad ignition stage. Again, you should be able to smell unburned fuel at the tail pipe.

Of course you could also have a blocked fuel filter and the alike. You can crack a banjo fitting and see if fuel spills out while the pump runs. A more elegant way is a fuel pressure gauge.

Good luck, get an assistant and head out to the airport one more time,
Ingo

Ingo

widgeon13 · 09-06-2009, 03:44 PM

Thanks guys for keeping the recommendations coming, I'll give it another go tomorrow.

widgeon13 · 09-07-2009, 09:03 AM

Rotor has some carbon build-up on the end and cap has carbon on all post contacts. Not very good pictures but possibly some help. Do not appear to be any cracks in the cap but I will spray w/ WD40 to remove any moisture and wipe out and put back together.

widgeon13 · 09-07-2009, 09:05 AM

jimbauman · 09-07-2009, 09:14 AM

Another point of failure that is common is the cylinder head temp sensor. If I recall, if that goes bad, it could cause a no-start situation. Bentley page 240-18 gives the simple test procedure....

JB

ischmitz · ischmitz's Garage

Any test results (ICV humming, spark, fuel) yet?

widgeon13 · 11:24 AM

ICV is humming but won't do the fuel check until possibly tomorrow and spark as well since I don't have any spare plugs. Have some other things to get to this afternoon so I don't end up in divorce court.

When I did the spray starter fluid into the ICV yesterday, I did smell the odor after cranking the engine.

The cylinder head temp sensor is going to have to wait as much as I'd like to dedicate more time.

Kapota · 09-07-2009, 11:00 PM

i had such problem too chek reference and speed sensors

widgeon13 · 09-08-2009, 03:40 AM

I have a bunch of stuff on order and it will be a few days before everything is here. Dist cap, rotor, plugs, sensors, 2 DME relays, coil and fuel filter. We'll see how long my patience holds up. I'm certain it will be something that I didn't order. Murphy's Law!

911FASCINATION · 09-08-2009, 09:25 AM

Hi Guys, I'm having similiar problems as Widgeon with my 84 Carrera. I've got the huge Interstate battery out and on the concrete, which is really tough to take in and out for me, (I'm very tall and have a bad back.) I'm new at the DIY stuff so please excuse the simple nature of my questions: Can I leave the battery out of the car and attach my emergency jumper cables to it and to the + and - battery clamps attached to the car? Thanks

ischmitz · ischmitz's Garage

911fasciation: the simple answer is: NO !!

The batttery is an integral part of the car and without it the alternator will produce transients that will damage electronics. Never run the car without a battery.

Ingo

widgeon13 · 09-08-2009, 01:05 PM

Well the 2 new DME relays arrived and I tried one, no joy. Also checked resistance on coil and that looks good.
Freakin frustrating!

ischmitz · ischmitz's Garage

Have you measured the sensors (resistance between signal leads should be around 1 kOhm and there should be no conductivity between either signal lead to shield (GND)?

911FASCINATION · 09-08-2009, 03:41 PM

Thanks Ingo, So even though the battery will still be attached to the car's battery cables the whole time, (with emergency jumper cables and the battery on the ground in front of the car), seeing if it will start with this setup is detrimental to the electronics?

widgeon13 · 09-08-2009, 06:43 PM

Quote:

Originally Posted by ischmitz

Have you measured the sensors (resistance between signal leads should be around 1 kOhm and there should be no conductivity between either signal lead to shield (GND)?

Think the reading was 1.1 K ohms.

ischmitz · ischmitz's Garage

As long as the battery stays in the circuit you are fine - it is needed to make sure the voltage regulator . But as soon as one of the jumper cables comes off there is a chance for a short and/or damage to the electronics. And make sure the battery is not a dud (dead as a doornail)

Cheers,
Ingo

kidrock · 09-08-2009, 09:58 PM

Widgeon,

it looks like you've pretty much run the necessary checks. I think it's safe to replace the speed and reference sensors now...I just don't like to throw money at something without making all the pertinent diagnostics first.

Keep us posted.

911FASCINATION · 09-09-2009, 06:57 AM

Thanks Ingo, Sounds like hefting that huge battery back into the tray is the only way to go. Like widgeon, I have to drive quite a distance to work on my car, so I was thinking if I left the battery out most of the time it'd be easier. I'm in the process of doing the simpler checks on my 84 Carrera, I've already replaced the DME relay, got about 5 minutes of run time before she cut off. Looking at the grounds I've got some sanding and cleaning to do-Thanks again!