Sputtering and stalling

[CurvyRover]

A funny thing happened on the way home from the grocery store. Our rover started sputtering but only under certain conditions. Motor will idle fine and when gas peddle is pressed will rev up fine too. The problem comes when engine is under a load. It is very hard to get moving due to sputtering and stalling, but once it is moving it seems to do ok at a steady speed. but upon accelerating it sputters again, and does the same thing up small hills as well. So far we have added fuel additive, dropped the tank to check for debris, changed fuel filter. We suspect it may have something to do with the vacuum system or the air/fuel mixture, but we have not gotten that far yet. Any other ideas? Please hurry, going through rover withdrawls.

[OkieRover]

Air fuel.
Good call.
Clean your air idler valve.

[CurvyRover]

Well I cleaned out the fire trap and found a broken T fitting on the hose coming from the fire trap. Replaced that. Pulled off the idle control valve and found a little carbon build up which I cleaned off. I have tried to figure out exactly how it was supposed to work, which just from looking at it the spring loaded plunger lookes like it would compress against the hole the plunger fits into. But in playing with mine, I could not get the plunger to move and was wondering if it is mounted on a screw shaft? I am still having the same problems, plus I have noticed that it does not idle well once it is warmed up a little, not to mention it is difficult to start. Any other suggestions as to where to look?

[scuffdog]

sounds like it may be a fuel pump... I used a carter p74074 to rebuild my pump assymbly a while ago. Just for giggles try pulling the plug from the MAF sensor; if there is no affect on the running state, try cleaning it.

[Kevin88RRC]

Also check the temp sensor to the ECU.

[TerryS]

The Valve end of the IACV (called the Idle Air Control Valve) does not move when you take it out, and don't try to move it. The IACV is a small servo motor, and you are right, that is a threaded shaft. DO NOT connect it to the plug and power it up,out of its housing, or you'll be wondering where those parts flew off to.
The MAF (mass airflow sensor), Fuel Temp sensor and TPS (Throttle Position sensor are the three main culprits to a rough running engine (no, not the O2 sensors, they only tell the ECU to enrichen or lean out the mixture) You can easily check the TPS, and it's best done with a conventional meter type VOM (volt ohm meter), not the digital one. There are specific voltages you can check for at the 3 pins, but the simplest check is a resistance check, looking for a smooth rise (or fall, depending on which end or the resesitor you are checking. You need to connect one probe to the center (wiper ) contact, and the other probe to eother end of the fixed winding,then look for a smooth meter movement, with no jerks, or points where it drops then climbs as you move the armiture of the TPS. When a TPS goes bad, it is almost always at one of two spots on the sweep of the TPS wiper contact; at the rest point (where the engine is at idle), and at the throttle position where you would be at cruising speed.

[choffa@comcast.net]

Check for a bad cylinder, easy things first, with engine running, pull plug wire off each spark plug & listen (or hook up a tachometer) for the engine to drop rpm. If you find a cylinder that doesn't change, check the plug, wire, or fuel injector.

I just had a miss under acceloration. Found the electrical terminals inside the injector corroded which eventually broke leaving that cylinder without fuel.

Replaced 8 injectors for $150 with rebuilt Bosch injectors from:

www.lindertech.com

Runs like a champ now, better than before (original injectors with 150,000 miles).

CJH

[tlry00]

I had the same problems shortly after I bought my Rover last year. Spent months and big $$ cleaning, replacing, adjusting and finally I replaced the alternator and wham she was perfect. I even had the old alternator load tested and it passed within output range.

[deadboy1977]

where is the fuel T sensor on the 4.2's?

[MysteryTheatre]

I know it sounds simple but when was last time you changed the plugs? i have seen worn plugs create such syptoms, and i've seen worn plugs that idle and rev just fine but create a sputter under load. just my cent and a half. occum's razor : the simplest possible solution is almost always correct .i've also seen small cracks in the distributor cap create such symptoms .

[OkieRover]

[ohiorover]

good advice, cleaned air idler valve, no more rough running at idle. The paper/harden rubber washer fell apart when I removed it, what should I replace it with???:clap, seems to run fine without it.

[1994RoverLWB]

Mine did the same thing for a while. I had a FULL tune up...wires, dist cap...the works....started running like a champ

[ChamplainRover]

I've been through the rough-running world of the classic, and I know how frustrating it can be. It is particularly so when people are making suggestions (all designed to be helpful, of course) but using terms to describe parts with which I am (or was) unfamiliar. You're then left either to ask a follow up question (e.g. What's a TPS and an IAC or a RunDMC? Should I ask the FCC?) or to spend a long time googling to find the answer.

All of this is to say THANK YOU to Okie for making the effort to take and post the pictures! For newbies this is more helpful than I can say!

ChamplainRover

[m1sandman]

I'm having a problem keeping the truck idling... I've replaced the IACV with a new one and I don't get the up and down with the idle anymore, but when I roll up on a stoplight, if I don't keep my foot in it, the truck dies. I don't want to hijack the thread at all, but are all these troubleshooting tips good for my symptom as well?
Thanks much!
Steve
Tampa, FL
91 RRC County
91 RRC Hunter