Need some help, guys

[Dave]

I need some help with this issue I'm having with our van. Upon starting it cold it loads up with a lot of fuel upon cranking and once started it idles like crapping, spewing blue smoke. To compensate I have to peddle it up to about 2,500 or so to keep it alive. After a few seconds it settles down and it idles fine. But it idles at low 10's in the A/F.

Once warmed it stays to 14.7. Now this problem has been going on for a week. I threw a MAP at it, redid the vacuum lines, threw in a new coolant temp sensor, and a HEP. Since then it was fine. All of a sudden it came back. So, I unplugged the battery and let it sit. Nothing. Backed the fuel pressure way down... nothing. Checked the coolant temp, while at 140-150* it was at 2.9v. Seems normal. Checked the MAP at idle, .7 - normal.

Now when it's warm it still idles around 14.7 but once boosted up over 2psi it fell on it's face, rich. So I threw a 91 5spd computer in it and it seemed to solve the problem... Everything was fine. I let it cool off and start it again and it started idling at low 10's again. :bash:

I've even thrown brand new RN12YC's at it, a different coil, checked the plug wires, I double checked the ECT, it checked out fine. The only thing I can think of at this point is it's an intermittent stuck open injector. I'll pull the rail and prime it a couple times to see if it's leaking. But again, it's intermittent.

Fuel pressure is at 40psi base. Alky lines are even unplugged. Any ideas or thoughts are appreciated.

[turbovanman²]

I would check for leaking injectors or a bad FPR. Maybe take out the fuel rail when warm and watch them as it cools down, or have a tray underneath and see if there leaking down. Are they stock injectors?

[BIG PSI]

They are plus 40's..........

If we have to to pull the FI are there places to have them checked or rebuilt ?

Chuck

[Mike_Shepard]

Big Chuck little Brian. R/C engineering can service the injectors.

http://www.rceng.com/index.aspx

[Dave]

Slapped in an old, known-good working set of 42pph's... still messed up. Next idea is a bad AIS... now it sits fine when boosted up, but as soon as I snap the throttle shut it goes fat and dies.

[Dave]

Replaced the entire throttle body assy. with different TPS and AIS sensors. Still did it. If I let it warm up a little it will calm down, but the idle does hunt between 13.1:1 and 15.1:1. Part throttle operation runs a little rich as well with still only 40psi base fuel pressure. Beginning to look at the O2 sensor.... hmm...

[Dave]

Here's a video of what's going on.

http://videos.streetfire.net/video/R...ich_183891.htm

Also, replaced the O2 sensor with another known good one. Same thing. This problem would normally point to an ECT sensor but reading 2.8v at ~140*F is normal.... I'll try and throw a new one at it. Half the problem here is I'm only using known good or used parts to try and solve it. The other half is I have no diagnostic equipment to plug in.

[turbovanman²]

Personally, half the stuff you've changed won't affect running rich.

Your coolant sensor is no good, 140F is too cold, it should be 180-195 depending on which stat you have. I would also triple check MAP vacuum and that its a good sensor-take one off a know running car/van.

Ox sensor unless stuck, will not make it that rich.

The things that make it rich are-Coolant, MAP, CAT to some degree, fuel injectors and fuel pressure, to which you've ruled out some of them.

[zin]

This problem would normally point to an ECT sensor but reading 2.8v at ~140*F is normal.... I'll try and throw a new one at it. Half the problem here is I'm only using known good or used parts to try and solve it. The other half is I have no diagnostic equipment to plug in.

Are you reading the voltage off a scan tool or by probing the sensor? If you are probing, the computer might be seeing something different, that is there may be something in the wiring between the sensor and the computer. Also, are you seeing this voltage when it is running like crap or? My gut says it's something to do with the CTS or Map, but the voltages seem correct, but are they consistent?

Best of luck!

Mike

[Dave]

Are you reading the voltage off a scan tool or by probing the sensor? If you are probing, the computer might be seeing something different, that is there may be something in the wiring between the sensor and the computer. Also, are you seeing this voltage when it is running like crap or? My gut says it's something to do with the CTS or Map, but the voltages seem correct, but are they consistent?

Best of luck!

Mike

That's the thing is that I can't read the sensors while I'm driving, but it does it only at idle. So when it is running like crap this is what I'm seeing. MAP .7v-1.1v because it misses and drops vacuum, ECT 2.8v because it's still a little cold, Simon. I'm hesitant to measuring it hot because the damn coolant feed line gets a tad warm while back probing.

I haven't back probed the terminals at the socket for the ECU yet. I'm waiting to see if Al will let me borrow a scan tool that will communicate with the van. Then that will tell me what the ECU is actually seeing.

So far I think I've narrowed it down to an ECT sensor-least likely, a bad AIS, it really only does it at idle, or a VSS as this commands the AIS. Out to Chrysler tomorrow for some new stuff.

Thanks for the help so far guys!

[turbovanman²]

Forgot to mention, low vacuum will cause the same problem.

AIS has nothing to do with it unless it doesn't work and your idle is like 500 rpm.

The way it sounds, its like when you set the timing and unplug the CTS.

[Dave]

Forgot to mention, low vacuum will cause the same problem.

AIS has nothing to do with it unless it doesn't work and your idle is like 500 rpm.

The way it sounds, its like when you set the timing and unplug the CTS.

Agreed with the low vacuum, but from what the MAP output is supplying it is staying true that there are no leaks. I even pressure tested all the vacuum lines by supplying 40psi of air into the main vacuum feed into the block and sprayed water around all the fittings and lines. I did found numerous leaks but fixed them all.

I thought the AIS might affect it by in which not allowing enough air to pass and starving the intake of air but still dumping in the same predetermined amount of fuel. It should have, however, set a code. And it's clean...

The ECT does make sense. I will hopefully have time to replace that as soon as it comes in.

Thanks Simon!

[DodgeZ]

Have you checked the intake?

[unluckyty]

What alky injection system are you running? If it is Devil's with a progressive controller, that uses map input. If it is disconect it an see if it helps.
I had issues with mine in the past.

Greg

[zin]

What alky injection system are you running? If it is Devil's with a progressive controller, that uses map input. If it is disconect it an see if it helps.
I had issues with mine in the past.

Greg

Interesting, the problem seems to be related to the MAP or CTS, the two biggest factors in fueling, so if the Alky controller is messing with the MAP signal, on a hit or miss basis, that could very well be it!

Best thing here, of course, is to get a scan tool on it, especially if you can get on that will data log, then you can review what the computer is seeing when its messing up. I'm really leaning toward something messing with what the computer is seeing. I'd say remove anything connected to the wiring that isn't factory and see what the scan tool says.

Best of Luck!

Mike

PS Might not be a bad idea to check the ignition timing and the cam timing, might have skipped a tooth, that can give you fits! Though that is a normally all or nothing kinda thing...

[Dave]

Have you checked the intake?

I have not physically checked it, but again with any measurable vacuum look it would appear on the MAP input. Not a bad idea though.

Good ideas on the Alky control unit, but I do have just the base kit with the mechanical pressure device. No wires are contacting the MAP input signal. I will absolutely have to get a scan tool on it and review the data.

On that note what should I be looking for in terms of vehicle speed sensor voltage vs mph and AIS motion? Is the AIS meatured in counts, and if so how many should I be looking for under what conditions?

Thanks guys!

[Dave]

Found out it was the ECT sensor. The new one was bad as well! Found out when I hooked up the scanner and it was reading colder than the battery.... hmmm.. That and the distributor timing was out. Oh and the alky magically decided it would like to work again.

15psi with the alky it tears it through 1st...

[IROCNOROLL]

Agreed with the low vacuum, but from what the MAP output is supplying it is staying true that there are no leaks. I even pressure tested all the vacuum lines by supplying 40psi of air into the main vacuum feed into the block and sprayed water around all the fittings and lines. I did found numerous leaks but fixed them all.

40 psi will probably make leaks that were not there?

I thought the AIS might affect it by in which not allowing enough air to pass and starving the intake of air but still dumping in the same predetermined amount of fuel. It should have, however, set a code. And it's clean...

If IAC was not right, the idle speed would be affected, not the the mixture. And the O2 is not used for the first 2 minutes of run time minimum after a cold start. O2 has no input or effect on a cold start.

The ECT does make sense. I will hopefully have time to replace that as soon as it comes in.

You might also see the same result if the coolant level is low, and the sensor is sitting in air until the engine runs long enough to have a little coolant expansion in the system, providing the sensor with something real to sample and report back on. They will not read air temps very well, and if they do it is usually way off what the actual engine coolant temps are. This will also make for black smoke and chug at idle on a cold start.

Like Simon says, 140 deg is too cold for a warmed up running temp.

[turbovanman²]

Glad you found some issues,

[zin]

Glad you found some issues,

ISSUES?! If he's a true TM'r he does not have issues!

He's got SUBSCRIPTIONS!

Mike

Glad to see you found something to correct, hopefully that will do the trick! Aren't those damn scan tools worth their weight in gold when you have these kinds of problems?!