2.2 and 2.5 Liter Mopar Engine Repairs

See our page on building a PCV oil canister to prevent PCV system oil leaks.

MAP sensor advisory

Dead MAP sensors are the bane of a 2.2/2.5, and one of the most common causes of dead vehicles. Fortunately, we were told (by an anonymous source using our form), “There is service advisory and an available air bleeder valve kit to prevent intermittent operation and premature failure of the MAP sensor. The valve allows a small amount of dry air into the MAP vacuum line to prevent a condensation buildup. It’s a low cost add-on, inquire at the dealer for the part. I used up six MAP sensors before finding out about this - haven't lost one since.”

Backfiring

Ralph Mazeski wrote that his 2.5-liter 1993 Acclaim was backfiring through the throttle body at idle, about once a second, making it virtually undrivable. It happened suddenly on a cold startup with no previous symptoms. No codes were set. Items checked include wires, plugs, coil, timing, vacuum leaks, compression, MAP sensor, TPS, and grounds. Finally, based on a Net tip, Ralph opened the valve cover and found that the rocker arm had fallen off the #4 exhaust valve; it was just laying there, with no obvious signs of damage or wear. The lash adjuster was solid, not spongy; it was a rebuilt head and Ralph believes the problem was excess wear on the valve stem tip. He installed a new rocker and lash adjuster.

Dan Minick wrote:

On any 2.2/2.5 front wheel drive Chrysler, oil changes are accessible from the top, one only need to slide underneath slightly to remove the drain plug. No need to jack the vehicle up. Same with 2.6 engined Mopars, although a little more reach is required to reach the oil filter around the manifolds.

Belts on a 2.2/2.5 all have a square tightening spot to put a ratchet.

Radiator--2 bolts, couple of hoses and it's out.

CV axle-remove a wheel, axle nut, 18mm pinch bolt, pry the lower A-arm down and pull out the axle.

Disintegration of the vacuum hoses

Over time, the vacuum hoses may disintegrate where they go over the engine. The solution is to replace them, as you might expect. One set goes to the vapor canister; this set includes two vacuum check valves. Twin vacuum hoses come from the throttle body, meet, and join before running to the vapor canister relay. We don't know why. Another hose goes from the wastegate to the turbo solenoid which is right next to the vapor canister relay. You can't get the solid pipes used by Chrysler any more, just use ordinary vacuum hose (for the vapor canister line, you need to use fuel line hose) with standard connectors.

Sticking throttle

Tim wrote: you may want to check the idle air control (IAC) valve in the throttle body. They can get sticky after a while. The best way to clean that is to remove the throttle body, remove the IAC from the throttle body and clean it and the hole it came out of. You'll need some small torx bits if it's like mine. Alternately, you may be able to clean it enough to 'get by' simply by spraying some carb cleaner at the IAC outlet in the throttle bore. You'll have to open up the throttle blade to see it. It's been a while since I've had to do it so I'm a little shady on that point. After a while, a ring forms in the IAC passage and the plunger can't move by it smoothly, if at all.

Hydrocarbons or running rich

John Auto Tech noted that the 2.2 / 2.5 was "notorious" for charcoal canisters becoming saturated with raw fuel, due to the positioning of the cansiter below the fuel filler neck. The result is higher hydrocarbon levels and symptoms of running rich (despite the oxygen sensor working correctly).

Belt squeaking

John Auto Tech wrote: "The alternator serpentine belt is known to squeak due to the alternator being out of alignment on the 2.5L engine . To check this (as a possibility) use a small prybar and shift the alternator forward and back on its pivot point and see if the noise goes away. There is a shim available to reposition the alternator in the event that this is the noise."

Early valve cover leakage

An engine designer wrote: "We had a problem early on with oil leaking out of firewall side of 2.2/2.5
valve covers after RTV was eliminated in favor of a gasket. The attaching screws were not shortened to compensate for a thinner walled valve cover, which resulted in the screws bottoming out. They 'torqued up' all right, too bad it was against the bottom of the hole instead of the valve cover.........a dab of RTV was still necessary at the inner bend above the bottom boot (near cam cap parting line)."

According to the FAQ:

Lemon-Aid Used Car Guide: "1989-93... cylinder head and oil pan gaskets are prone to leaking." ... "1990-91 - Owners can get a new cylinder head gasket cover on models with 2.2L and 2.5L engines." (Jim Hoare)
p/n 4773193, a new valve cover (1994?) forms a superior seal on 2.5 engines, maybe 2.2s too.
Bob Meyer says: The valve covers on emission-controlled cars are vented through the inlet hose from the air cleaner to the valve cover and the PCV valve from the valve cover to the throttle body/intake manifold. If you are having a problem with valve cover oil leaks, then you should check whether these hoses, or the small crankcase air filters in the air cleaner, are blocked first before you reseal the valve cover. Around 1987, Chrysler [along with Dodge and Plymouth] switched from using a gasket to using RTV. In 1994, they switched to a 1 piece valve cover from a 3 piece cover.
Mike Manning informs us that recall #467, issued in 1990, covers the valve cover gasket; he says that the gasket was replaced with blue goo. Once this stuff has set up, the cover needs to be re-tightened. We don't think the dealers usually do it correctly. Mike finally replaced his with a cork gasket.
Paul F. Schikora : Went to NAPA and got a gasket set and a bottle of gasket goo (orange colored stuff). Took my time cleaning the surfaces completely and applied the gasket & goo per instructions. No more leak. However, I'm sorry I didn't take the time to reseal the PCV connection cover. It's always bled quite a bit of oil into the valve and air filter. (Note: this was for 1987 model, which had a gasket).
JoDee McKenney says: I'd use the gaskets and the high temp silicone on each of the metal surfaces. This allows a way to seal the parts together and still get them apart later.
- Daniel Stern warns: DO NOT DO THIS on an engine with mechanical lifters because there will be hell to pay when it comes time to adjust the tappet clearance.
Duane P Mantick provides TSB 09-17-89 which advises replacing the original cover with one using RTV. The "cylinder head cover kit" is PN 5241066 and contains the cover, five screws, 2 end seals, four studs, but not RTV sealer PN 6500435. This TSB applies to "1989-1990 all domestic vehicles with 2.2L or 2.5L EFI engines"
Michael J. Challis <bigchall@aone.com>, a Chrysler Master Tech, wrote that Mopar RTV silicon works well: "The trick to this stuff is to have a clean surface. Use brake parts cleaner to remove oil so you have a dry surface for the RTV to bond to."
Oil leak from manual transmission: Applies to all cars and minivans with the manual trans A-523, A-543, and A-568 (most of them). The TSB (21-24-93) says that "vehicles that are in the dealership for any other reason should also be inspected for this leak condition." What is replaced is a remote vent assembly in place of the existing lock pin, and a new linkage adjusting procedure for future service.

Chris Zwingli wrote:

If you have to replace a leaking valve cover gasket on the 2.5 with the 4-piece gasket(2 rubber end seals and 2 cork side rail gaskets) do yourself a favor and use the Victor Reinz set for this application. Do not use the FelPro set. The Victor Reinz gasket is about $2 cheaper and actually does a much better job of eliminating oil leaks-I found this out by accident after unsatisfactory results with 2 FelPro sets.
If you find that the spark plugs are rusty, replace them with Champions.
I do not recommend the use of Slick 50 on Chrysler products-it caused slow leaks of the rear main oil seals on both of my vehicles. Fortunately, draining the engine oil and replacing it solved the problem on both cars('90 Dodge Spirit and '96 Plymouth Neon).
If you find oil in the air cleaner housing, suspect a partially plugged PCV system. This can be solved in the 2.5 TBI by using a can of GM Top Engine Cleaner. Just follow the directions on the can.
If you have to replace a leaking heater valve, be careful and compare the old one with the new one if it is aftermarket. Some of the aftermarket valves are taller than the original factory part and will cause interference problems with the air cleaner housing, leading to reinforcing ribs on the air filter housing rubbing through the upper hose between the heater core and heater valve.
While I am on the subject of heater valves, do yourself a favor and cut the old hoses off the heater core inlet and outlet instead of trying to twist them off. Twisting or pulling off the hoses could provoke the heater core into leaking- not a happy prospect.
While I am on the subject of hoses, it is possible to replace the z-shaped molded hose between the intake manifold and the heater valve with plain old 5/8" heater hose-just be sure to let the engine get to full operating temperature after you refill the cooling system. The heat will allow the hose to adapt itself to the new situation with very satisfactory results.
If you replace the transmission fluid and filter on the 3-speed auto trans, make things easier for yourself the next time by using a cork gasket instead of RTV. The cork gaskets work fine if you make sure that the mating surfaces on the transmission housing and pan are clean and free of any old material and that there are no bolt hole dimples in the trans pan.

More leaking valve cover gasket fixes

"kd5inm" wrote: Today I took the valve cover loose and cleaned everything up and reused the rubber end pieces and used O2 sensor safe red RTV to "make" a gasket for the valve cover. The old gasket was the two paper pieces on back and front and rubber on ends, the rubber was good and it didn't leak from sides, but did leak from backside and frontside of the engine (looking at engine from front of car). I applied a thin coating of RTV on both the valve cover and on the head and then let it get tacky, then I reassembled the valve cover and tightened things snug but not too tight. I ran the engine after everything was buttoned up and no oil leaks so far.

Bohdan Bodnar's Notes

I was playing around with my 1986 Le Baron (2.5 liters TBI with a/c) and thought that some of the more technically inclined readers may be interested in my experiences. Here are the problems I was addressing:

On a hot engine, the idle would "randomly" drop abnormally low (but not low enough so as to stall the engine) and would be corrected. During the correction, the idle sometimes overshot what appeared to be the desired idle rpm. This problem has been around for the past few months, but it's been COLD in that garage...
Intermittent engine knock developed in the past two weeks.
Records of fuel efficiency showed a marked decrease in efficiency (in miles/gallon) in the past two weeks.

Now, for the first problem...

A weird idle problem on a hot engine (or, for that matter, ANY drivability problem under this condition) usually implicates the feedback control system. However, this car had a new oxygen sensor (replaced 13 months ago). As expected, no trouble codes were stored. I connected an oscilloscope to the O2 sensor and let the engine idle.

My opinion was that the sensor's output wasn't "steep" enough (the transition from a high reading to a low reading and v.v. should be FAST -- almost a step response). The reference voltage the computer was feeding the sensor was 438 mV, not the 450 mV I'd expect (but this isn't a big deal -- computer systems put an "error band" around the 450 mV threshold and ignore sensor readings in this band -- this is like trying to operate a digital logic gate in the "forbidden region"). I next decided to check the average a/f mixture.

The easiest way to see what the a/f mixture is is to use an ignition oscilloscope. Since I don't own one, I did the next best thing -- I 'scoped the primary side of the ignition coil. On a well operating engine, here's what I'd expect to see:

Firing line (ignition voltages) about the same for all cylinders -- no more than +/- 20% variation between the highest and lowest. If an ignition oscilloscope was available, I'd expect to see the maximum differences to be less than 3 kV. If the firing line is jumping all over then the a/f mixture is screwed up.
Spark time ("burn time) to be in the range of 0.85 ms to about 2.2 ms. Also, the spark line should be somewhat jagged AND FLAT. A line which rises upward toward the end of the burn period indicates lean misfire. Typical spark time is around 1.6 ms.
Firing line to spark line voltage ratio should be about 4:1.
At least 5 coil oscillations after the spark ceases (some computerized diagnostic gear -- e.g. Sun's "Modular Computer Analyzer" -- look for a minimum of 3 oscillations).

In my case, the firing line to spark line ratio was substantially higher than 4:1. This is attributed to using non-Chrysler ignition wires which have MUCH more resistance than Chrysler's specs (these are Autolite wires). The firing voltages were almost all the same (indeed I couldn't tell the difference between the cylinders). Spark time varied from 1.9 to 2.1 ms and the spark line was almost ruler-flat. Around 10 coil oscillations were present.

This is a classical example of (1) abnormally high secondary resistance (2) perfect ignition coil (by the way, this is a Wells coil -- about a year old) and primary circuit, and, possibly, an engine running rich. Temporarily shorting out one of the cylinders showed that the firing voltage for that cylinder did not change appreciably -- hence, confirmation for the fact that the secondary resistance is too high. Also, the spark voltage did not change appreciably.

Based on these observations, I replaced the oxygen sensor. The new sensor's response is much better (closer to a step function). Why did the previous sensor fail? The most probable answer is that the engine blew its head gasket a month after the previous sensor was put it. Silica in the coolant contaminated the sensor and caused its response time to increase. Eventually, the computer would have caught the problem ("eventually" meaning at least a year from now). Now, on to the engine knock problem.

When diagnosing engine knock, I look at two things: fuel quality and EGR operation. Only if these two are eliminated as culprits do I look to see whether a lean a/f mixture exists. Since the idle looked ok in open loop, I discounted fuel quality. I tee-d a vacuum gauge into the EGR valve's vacuum line and, with the engine running, slightly opened the throttle.

With no appreciable engine load, I expected to see about 5" Hg control vacuum. Instead, I measured full ported vacuum. To understand what this means, one has to understand how the EGR system meters exhaust gasses.

The backpressure transducer has two vacuum hoses and a stainless-steel backpressure pipe feeding it. The pipe feeds exhaust gas pressure to the transducer. One of the vacuum ports goes to ported vacuum (or, the EGR solenoid if this is the 2.2 turbo or multipoint injected engine) whereas the other feeds the EGR valve. If the exhaust pressure is high, the transducer opens and allows control vacuum to move the valve's pintle up. This increases EGR. If the exhaust pressure drops, the transducer closes and allows atmospheric pressure to enter the EGR valve and close it. By oscillating back and forth very quickly, the backpressure transducer allows the EGR valve to see a smoothed control signal and thus open only a certain amount. The amplitude of this (pneumatic) signal is a function of engine load, rpm, etc.

Since the transducer was applying full ported vacuum and since the engine didn't bog down when the throttle was slightly opened, the implicated culprit is the EGR valve. I connected a vacuum pump to the valve and pumped up about 15" Hg vacuum. The valve's pintle did not move.

A new valve/transducer assembly will be put in within the next two weeks.