EFI question

Robb · #1 (**permalink**) 05-22-2003, 07:58 PM

Hello. I have a question and I was thinking perhaps one of you small block cobra runners (using EFI), might be able to help me with.

It is not cobra related, but without searching around on the net and looking, I don't really know where else to look.

I got a 93 Ranger with a 3.0l V-6 fuel injected engine.

It has a particular problem, that I think is not engine specific, but "system specific".

When its cold, in the morning (worst in winter), It starts fine. But when I put it in drive and go to accelerate, it feels like im pulling tens of thousands of pounds on a trailor. Absolutely no acceleration. Gearing, is irrelevant. As the truck slowly starts accelerating, the engine then starts to "pulse". Pull (accelerate) decent, then falls on its face (no acceleration), then pull, the fall, then pull, then fall... As speed picks up, the pulsing gets closer together. It does it worst in winter, but also on hot summer days. (though its less noticable). After driving about a 1/4-1/2 a mile, the problem is gone. I assume the engine has warmed up enough that the problem has temporarily went away.

Anyone have any ideas? I ran some fuel injection cleaner through the engine, but I realize this is not the same as a professional fuel injection cleaning job. Results: no change.

Im not sure if I've tried it, but I think i might get some air intake cleaner, and work over that valve. (I forget the name of it) on the plenum.

I also believe it was doing this problem when I took it to the mechanic to have the mass air flow sensor changed. It came back with no scan code errors.

You can email me, if you have an idea. I'll try to check back as soon as I can.
Thanks in advance.

(btw, while its not cobra specific, this same problem might inflict someone with a fuel injected cobra.. .so, I guess it is sort of on topic).

-Robb

robb@kc.rNOr.cSPAMom

wingnut13 · #2 (**permalink**) 05-22-2003, 09:23 PM

Hi Robb, Just a question. Did you check out you fuel pressure? A clogged fuel filter or a finniky fuel press. regulator could be the problem. Alos does the engine "surge" while just idling? Your Idle Air Control (IAC) on the intake should have nothing to do with how your truck runs at other than idle. It's only job is to bypass enough air when the trottle is closed to keep the motor idling at the right RPM. I think it was a good post, we can all learn more about FI problems that we may encounter on a Cobra project. Hope you fix your problem. -wingnut13

Robb · #3 (**permalink**) 05-23-2003, 06:11 AM

Don't remember doing it, but my maintenance book shows a new fuel filter a few thousand miles ago.

I would have changed it, believing it might have been the problem.

Did some more research on the net, found a man that had a similar problem that was cured when a mechanic changed his 02 sensors.
That was something I was going to try, but never did for cost. (at time, thought the truck had 1 02 sensor, couldnt afford to buy both).

As it has 82k, I will soon change the 02 sensors, timing belt (if it has one), and some other long term maintenance. Will post results, afterwards.

-Robb

sllib · #4 (**permalink**) 05-23-2003, 08:42 AM

Robb;
I think what your truck needs is a small block V-8. If you go on some of the Ranger sites there is a lot of info on swaps, and a swap might keep you happy until you get a Cobra. I have a 2000 Ranger and want to go the swap route, but the truck is too new for the after-market and I'm not good enough to wing it. Good Luck.
Bill S.

wingnut13 · #5 (**permalink**) 05-23-2003, 10:44 AM

Robb, he does have a point, My 88' Ranger is getting a 302

Sizzler · #6 (**permalink**) 05-23-2003, 03:13 PM

I don't know why the o2 sensor would affect cold-start operation.
During warm up the EEC isn't reading the o2 sensor.

More likely something like moisture in the throttle-cable or in the vaccuum tubing leading to the MAP sensor, or the MAP sensor itself.

It could also be distributor related. Not sure, does that use a TFI module? Though I think problems with the TFI manifest themselves at high-temps, not cold.

Excaliber · #7 (**permalink**) 05-23-2003, 04:05 PM

I wonder about the timing of WHEN the EEC starts to read the O2 sensor, might be soon enough to be a "player" in this scenario.

Three wire O2 sensors use the third wire the "heat them up" quicker on a cold start condition.

MAP sensor is a good call. No "codes" is the most troubling part of this thing!

Symptoms would indicate it happens at a time when the engine needs a "rich" mixture, so fuel pump pressure should be verified.

Ernie

RICK LAKE · #8 (**permalink**) 05-23-2003, 04:46 PM

Robb Hi Robb Does your truck have a Mass Air flow sensor. If it is a hot wire style the wire may not be geting a go signal until it heats up. DON'T spray cleaner on this wire. Take it to A dealer ship and have the gram count checked. I would look at the fuel pressure also have a volume check done. Rick Lake ps on GM cars if you unhook the MAF sensor the light comes on but the car will run better, thensensoe is bad. I donot know if this works on ford.

Robb · #9 (**permalink**) 05-24-2003, 02:19 PM

Hum...
Read on one forum, the company that sells yearly online maintenance reports for your car (forget their name, though I had a subscription), that it may indeed be the wire in the mass air flow? sensor. Said that paper lint from cheap air filters gets on the wire, contaminating the grams per second count, which can cause similar problems.

Going to investigate further, re-connect a code scanner, change the o2 sensors (they need it anyway), and I'll get back with you all about the results.

-Robb

Robb · #10 (**permalink**) 06-16-2003, 08:43 PM

Follow-up....

New oxygen sensors did not solve the problem.
Spraying the sensor wire down, to insure paper fibers werent on it, did not solve the problem.

I got 2 choices left:

Possible dirty injectors, causing it to run poorly, (it doesnt act like that is the problem, however)... and taking it back to the dealer and having a trained mechanic diagnose it.

What is anyone/everyone's opinion on bottled fuel injector cleaner, at the auto parts store? (assume premium brand/price).
How does this compare, to taking it to a mechanic and having them run the fuel injector service. (where they hook special lines to the engine, run a special chemical through it, etc) ?

I got 83k miles, its 10 years old. Dont think it could necessarily hurt, as preventative maintenance, at minimum. However, I used to run a jar of gumout through the engine every oil change.

-Robb

Excaliber · #11 (**permalink**) 06-16-2003, 10:10 PM

Well injector cleaner can't hurt and might help. But for some reason my gutt tells me (based on your symptoms) it's not injector trouble. I'm still suspicious of fuel pressure or the fuel pressure regulator (which has a vacuum hose on it. is it nice and tight)?

Fear not about the O2 sensors, at that kind of mileage it was a good call to replace them anyway. What about that fuel filter?

Edit:
OH!! Just thought of something. Clogged up catalytic converter OR internally collapsed exhaust pipe would give symptoms MUCH like you describe! By pass the exhaust if at all possible for a "test drive". I once had a Buick (customers car) with an internally collapsed exhaust pipe that took FOREVER to diagnose. It was real close to where it bolted on the exhaust manifold, the metal inside all folded "inward" and restricting exhaust big time!

The "clue"? Manifold vacuum would be steady to a certain rpm and then DROP like a rock when it hit just the right rpm!

Ernie

HighPlainsDrifter · #12 (**permalink**) 06-16-2003, 10:49 PM

Robb,
Most likely the TPS sensor, on the throttle body, 1" oval held on with 2 screws, should only be $30 at Napa. Just plugs into a factory conector. The carbon in the variable resistor breaks down and doesn't give the proper voltage[ 0.8 to 5 volts ] to the computer.
Good Luck,
Perry.

auto10x · #13 (**permalink**) 06-17-2003, 05:58 AM

Be sure to verify that the engine and ambient temperature sensors are operating properly. Then be sure the MAF / MAP sensor is OK. Then the TPS.
Good luck,
auto10x
Bill

Robb · #14 (**permalink**) 06-22-2003, 10:04 AM

Thanks for the suggestions, guys.

I myself thought it might be a bad cat.... but, not for certain.

Will do some more work on it, in the near future, let you know
how it comes out.

-Robb

Fred · #15 (**permalink**) 06-30-2003, 11:21 AM

Robb,
I have a 93 ranger, 3.0 liter six. I had a similiar problem where under acceleration, the motor would hesitate and pulse. This was not that many days after the cobra was started after a long winter and it was running poorly too. Revved the cobra and mice nests flew out of both side pipes. Thought my probelm with the Ranger may also be mice. Disconnected the Rangers inlet plenum and found a new nest just before the air filter. Cleaned everything out and it ran fine.

What about this 302 swap into a Ranger? I have a spare EFI 302. Will the transmission take the power or is it a engine/tranny swap.

Fred