Engine Code 32 EGR misfunction & engine balks at 1700 rpm

[rogermills]

1994 240SX automatic 155k miles

I have been scanning the forums for help on my check engine light with an EGR code 32. I noticed NISTECH's other postings on this subject.

Bottom line first:

*** ". . . If the hose [under the BCT] does not appear to be an issue, slide your fingers up under the EGR valve while the car is idling and push up on its diaphram, the engine should stumble to a stall or drop to where it almost dies."

MY ENGINE RPM INCREASES WHEN I PUSH UP ON THE DIAPHRAM. ***

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*** ". . . If that doesnt happenthen you got passages plugged and need to clean them out [no fun] "

WHAT IS MY SITUATION; WHAT PASSAGES NEED CLEANING OUT?? ***

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I have many issues and I have tried to resolve some -

1) The 1994 240SX automatic drives rough at 1700 - 1900 RPM. Above and below that it is fine. If I accelerate REAL HARD from a stop (going into traffic) this is a dead spot that I cannot get by. The car balks and shutters at 1700-1900. I can get all the spunk I can handle if I keep the revs up.

2) Because of oil consumption, I had the 240SX S-13 engine rebuild at 140,000, about 1.5 years ago. Compression was fine before (about 140 average PSI) the rebuild, but is uneven now (two around 140, two around 160). Oil consumption DID NOT improve. No real noticeable smokes from the rear before or after rebuild. HEADS WERE NOT RETORQUED after rebuild.

3) Cat-back was replace 2 years ago, but I hear exhaust noise. I cannot find any leak, either around the cat converter or along the pipe(s). I would like to get the seemingly exhaust leak fixed before I start blaming something else. I have all the tin off after the part around the header-motor part.

4) The catalytic converter has not been replaced, to my knowledge. Original at 155,000. The oxygen sensor WAS replaced, along with the PCV valve with the rebuild 1.5 years ago.

5) Four nights ago I removed and cleaned the reeds in my AIV (Air Injector Valves??) unit. The hoses around the AIV and the black box are excellent. PLEASE NOTE: the vacuum activated valve at the top of the AIV is like NEW!! There is almost no carbon buildup at the upper half of the AIV, just at the reeds and the bowl below. I pulled 3 AIVs off junkyard cars to see how to clean the one on my 240SX, for experience. Two of these vacuum activated valves were in-operative, and one of them worked fine. My vacuum activated valve also worked fine, and it seemed exactly like new. I would put that vacuum activated valve in a cup of coffee, and drink the coffee, it was so clean!!

6) The BCT valve seems to work. At idle, I have no vacuum between the BCT and the EGR, but at higher engine speed there is vacuum. I used a vacuum gauge. I tried to push the EGR valve bottom when the engine had about 2000 rpm, but I did not see and noticeable effect in the engine speed. [***NOTE: Today I checked the EGR valve at IDLE, and the engine rpms increased when the engine should have almost stalled. ***]

7) The hose that connects the BCT at the bottom to something is solid, but it seems to have a crimp in it at the bend. Is does not seem to be a 90 degree elbow hose, but just a straight hose that was fitted to a 90 degree angle. I will look for the correct fitting elbow hose. NOTE: I pulled 2-3 BCTs off junkyard 240SX's and they ALL had deteriorated (torn - broken) elbow hoses. All three, so I thought that mine might be bad, also. But if I am getting vacuum to the EGR, does that indicate the hose is OK, even though bent?? The vacuum at the EGR valve from the BCT was not steady; it seemed to keep dropping at an even 2000 rpm.

8) I finally found out how to take an EGR valve off the 240SX. Easy. Now I have one spare (the other two were trashed in the experiment of removal). Are there any tests I could do on the EGR valve at my workbench??

9) Four weeks ago I took the '94 240SX to a 'Top Japanese' mechanic who only replaced the temperature sensor and timed the engine and reset the engine code light and charged me $340 for the experience. The engine light came back on the next day and there was no improvement. I got the temperature sensor from him (he did not want to give it to me) and I checked the resistance when I got home. Room temperature resistance was perfectly in the range. I did not feel anything would be gained by measuring resistance at 0 Celsius and 100 Celsius. As they say, 'resistance is futile'

10) Two weeks ago I took it to a recommended mechanic. This mechanic probably never saw a Nissan in their life, and he was on the cell phone asking people about the 240SX. I asked him ONLY about the rough running at 1700 rpm, and he installed a rotor and cap and said it is fixed and $100 please - thank you. Of course it is not fixed!!

11) I get very decent gas mileage with new NGK plugs - 27 mpg, but after 2000 miles, the mpg drops to way below 20 mpg, like 15-17 mpg. If I put new plugs in every 1000 miles instead of paying mechanics I might be better off.

12) I have a junk yard coil on my work bench, along with all the other pieces around the coil. Would this be a factor 9I think it might be, so that is why I pulled the ignition coil et al. I just do not know how to read the ignition coil to see if either is good, or if one is better. I will check the spark at the tips of the plugs.

It is FUN cleaning those reeds. They have a very nice feel and composition, just like the keys on my clarinet. And a nice heft to them. And the rubber base that the reeds sit on were a surprise. I could not notice that there was rubber and metal down there.

[NISTECH]

Ok I am not gonna hit all your questions here as I caught a couple things as I worked down your list that need to be addressed before you worry about any of the others as some may be symptoms of the big problem, You have 2 cyls that are quite low as compared to the other 2. At this point that is the one thing you need to be concerned with. That problem will have nothing to do with any of the electrical components as it is a mechanical problem. you need to check your valve timing,and do a wet compression test to see if your numbers come up.

[rogermills]

OK. I will check my valve timing (I will research and find out how to do that - Did you mean engine timing??) and do a wet compression check (I am very familiar with the air cooled VW bus engine, so I can do this wet compression check without any problem.)

The S-13 has only 15k miles since a rebuild, but I have no confidence in the shop that did it. I asked and wrote down that I wanted all the replaced parts, but I got nothing back, I saw the head on the work bench when it came out, but not after it was re-worked., before it went back in.

I asked the shop manager to replace the PCV with one I supplied, and he said that this engine did not have a PCV. Obviously not a competent shop.

Can you tell me what the torque should be on the head bolts/nuts??

Is it straight forward on removing the valve cover to get at the head bolts / nuts??

Thank you.

Barry sends

[NateDogg]

Barry, go to http://www.zeroyon.com and download the S13 Factory Service Manual.

The stock compression should be closer to 179psi. Did the rebuild include a hone and ring job? Usually low compression is caused by piston rings not sealing well.

In the manual you can find all the torque specs and everything you'll need about the EGR as well.

[NISTECH]

You will need to remove the cam shafts to gain access to the head bolts.

What I mean by mechanical timing is,make sure your crank and cams are in proper timing by looking at the marks on the gears. Download the manual Nate mentioned as it will help you immensly, If you need the engineering to Technician translation to anything in the manual post it and I will do my best to explain the real world definition of what the engineers are trying to explain in the manual.Do your wet compression test first to determine if the rings are ok.

[rogermills]

Thanks, all... It took me over an hour to download the 240SX 1990-1994 Shop Manual at home, on a 56KPS line!! And only 2 minutes at the office.

I printed the first 12 (of 175) pages from the EF & EC section. I am overwhelmed. My current experience is with air cooled Volkwagen buses, the type 2 bus with the type IV engine. To get to see the cam and crank in a type IV (or beetle - Type I) engine, I have to completely dismantle the type IV engine, and split the case!! I am learning how to rebuild the type IV engine as an on-going education: rings, wrist pins, honing cylinder walls, replacing air injection and fuel lines.... It took me a long time to understand that the type IV engine block came apart in two halves!!

So, my point of reference in all this is from a different perspective, and it takes some time before I get to understand a diferent concept, like the KA24DE engine.

** I have an owners manual for a 1993 240SX. It gives the spark plug's part number, NGK. I went to my FLAPS and they said the 1994 has a DIFFERENT spark plug than the 1993! I was 'shocked', I mean, it IS the same engine, right, just a convertivle / automatic...

Wet compression check I can do, but pulling the valve cover and the cam off to torque my head bolts / nuts and see the mechanical (vave) timing is too frightening for me to accomplish. And my problem is that I cannot find any mechanic in Northern Virginia (Fairfax) that I can trust on this 240SX.

So I am stuck. Without seeing the mechanical (valve) timing, I am stuck.

Is it possible to tell me (just give me a hint) what might be wrong when I push UP on the diaphram at the base of the EGR valve and the engine (at idle) accelerates (somewhat builds up speed)?? This would be realated to the engine code 32, EGR malfunction on a California car.

I will try to work the stumbling problem by trial and error. If I had thrown $450 worth of parts at the 240SX, i would have had a better chance of solving my stumbing at 1700 RPM than the results I got from those last two mechanics!!

Anyways, thank you all. I am discouraged.

Barry sendsSpringfield (Fairfax) Virginia

[NISTECH]

pulling your valve cover and looking at your timing morks is a very easy task, the only part you remove to do this is the valve cover. the cams are completely visable from that point.there are several pics in this forum on the timing gears on the 240.

on your EGR it seams virtually impossible for that to happen. When opening the egr valve as your doing it creates a huge vaccum leak to the intake the problem though is the air it takes in is lacking O2 since it is already run through the combustion chamber it has used it up. This is done to help cool the cylinder so Nox wont be created during detination of the fuel. It allows enough volume in but lacks the O2 to make the fire hotter. The only possibility I can thing of is either you have a fresh air leak near the base of the o2 [ like a leaking gasket (this has happened)] or the egr it self is drawing air in from the diaphram [never seen it happen or heard of it]

[rogermills]

pulling your valve cover and looking at your timing morks is a very easy task, the only part you remove to do this is the valve cover. the cams are completely visable from that point.there are several pics in this forum on the timing gears on the 240.

OK, I am facing my limits. If possible, I will have the '94 240SX's engine's heads and rings redone.. Plus the front and rear cam shaft gaskets, because it is now an oil leaker...

I printed out the majority of the FSM, double sided, as appropriate for my AUTOMATIC '94 240SX (No clutch or standard trans stuff).

I see in the FSM that there is a SEQUENCE to removing the head bolts. Perhaps my previous shop owner mechanic used his cousin in rebuilding my engine, so I absolutely do not trust this shop owner (or any, even if I am looking over their shoulder!!)

I want to pull a head from a junk yard and take it to a machine shop and watch the machinist rework that spare head. I think it may be a bit expensive, but I will handle the head and he will handle the tools. Besides, they are his tools!! My pay-back is that this mechanic chats your ear off, but I can take it!!

IF I get a good rebuilt head out of all this, I will approach another shop mechanic (one I have been using for the past 10 years, whom I have sat in the same pew with during church services, and whom my wife knows where he lives!!). He is somewhat honest (a deacon in the church) but will do what he thinks is best, even though we may have disagreements on what is best... He asked me why I didn't approach him for the re-build.

So, are there any hints on getting the head for the mechanic?? Should I get the cam shafts too?? and the valve cover?? Intake or exhaust manifolds. The whole engine, with fuel injection is just $150, but, I imagine, is quite heavy.

What to take, and what to leave behind. I am going out this Friday, 6 May 2005, before someone else strips the junk yard engine.

Barry sends

[NateDogg]

Well Barry you will probably re-use your existing intake and exhaust manifolds so dont worry about taking those, unless it is included. It's always nice to have some spare intake sensors lying around.

For $150 I would just buy the whole engine. Sounds like a good price if it's in good running condition. But that's just me. You'd need a few strong guys to hoist it/skid it into trailer if' it's on a pallet. It's about 400lbs IIRC.

I would leave the camshafts in the head because they are shimmed specifically for where the rest.

Good luck!

[rogermills]

on your EGR it seams virtually impossible for that [engine goes faster when Barry pushes up on the diaphragm] to happen.

When opening the egr valve as your doing it creates a huge vaccum leak to the intake . . .

I have a good, spare EGR Valve on my work bench.

It has two small vacuum line metal tubes (line ‘A’- comes FROM the BPT, and is on top of the EGR Valve, and ‘B’- goes TO?? somewhere and is swaged like a metal brake line into the cast metal base of the EGR Valve assembly, and seems ALWAYS open to air flow through it)

and the EGR Valve has two medium sized hole in the cast metal base part of the EGR Valve (‘C‘- big hole for exhaust gas to go TO the adjoining air intake manifold, and ‘D’ – a bigger hole for exhaust gas to come FROM the exhaust on the other side of the engine.)

The exhaust gas is ALWAYS coming from ‘D’ and going out thru ‘B’. Sometimes the exhaust gas ALSO goes out thru ‘C’, as well as ‘B’.

When the engine is idling, and there is NO vacuum coming from the BPT via 'A', then 'D' and 'B' are the only path for the exhaust air. I. e., the exhaust comes into the EGR Valve solid metal base via 'D' and some exits out via 'B'. The EGR Valve keeps the exhaust gas from exiting out ‘C’ until the next thing happens.

When the engine is running faster, there IS vacuum from the BPT via 'A', and then the diaphragm in the EGR Valve is drawn up by the vacuum, and this opens a path for the exhaust gases to come from 'D' and pass out of ‘C’, as well as 'B'. This addition Exhaust Gas [Recirculated] [EGR] now passing by ‘C’ and into the intake manifold causes a richening of the air/fuel mixture by reducing the air [the exhaust gas that recirculates into the intake takes up some of the space that the oxygen air would use] and the compression is still maintained high because the total gas volume is the same, giving a richer fuel mixture.

Richer air/fuel mixture = cooler burning engine. A given!!

Well, Barry has the engine at idle and warmed up, and Barry pushes up on the EGR Valve diaphragm with his stubby fingers. This allows the exhaust gas to recirculate into the air intake, enrichening the air / fuel mixture while maintaining the overall volume of gases to support the compression cycle. Barry was creating a richer A / F mixture at idle, and this is not good.

What!! If you have a richer A / F mixture without adding extra fuel, and keeping the compression up, and it runs cooler, what is wrong with that picture.

OK, the problem is that it ‘reduces power’….. When the engine is just tooling around, doing its own thing at a normal cruise speed, so what if you are losing 20% power. You aren’t using it, anyways!! But when you full-throttle hit the gas pedal, the EGR Valve will lose the vacuum from the BPT and the EGR Valve will CLOSE the recirculated gas flow out of ‘C’ and into the intake. This will give you the OPTIMAL air / fuel mixture (what is it, 7.4 air to 1 fuel??) for power.

Similarly, when the engine is idling, the OPTIMAL air / fuel mixture should be the target with maximum efficient power, and the EGR Valve should close off the flow of exhaust gases to the intake manifold.

Simple??

But why did Barry’s engine go faster when he introduced exhaust gas at idle. It should have choked (flooded??) the engine.

Well, it would have shown symptoms of flooding an engine if it was at the optimal air / fuel mixture to start with. But if the car was running too lean to begin with (Why is it running lean, only the big ‘G’ mechanic in the sky would know), and the mixture was increase toward the optimal level of 7.4 to 1, then it would be expected that the engine would (slightly) increase its idle speed.

Any ways, it does show that Barry’s exhaust gas will be recirculated when the diaphragm is lifted, as we have shown by mechanically lifting the diaphragm with stubby fingers at idle. The question is, does the diaphragm ALSO lift with the vacuum from the BPT when the engine is run at about 2500-3000?? Easy to check, no problem. If it DOES NOT lift with vacuum while it does lift with stubby fingers, I have a tested EGR Valve on my work bench, ready to go in.

[[FWIW, I also have one or two functioning BPT valves, and three extra sets of AIV reeds – one cleaned pretty. available on an as needed basis. Or I could package the stuff and sent to NISTECH for him to take apart or distribute.]]

I don’t want to stop this thread without asking a question, so here it is:

Where do I connect my hand held RPM meter at the engine so I can read the RPMs when I am under the hood. Make it simple, guys, and I may have a different coil than the earlier 240SX’s.

Thanks

Barry Burneskis'94 Auto Convert 240SX S-13 KA24DE [custom leather interior, if that matters]Springfield VA

[rogermills]

I would leave the camshafts in the head because they are shimmed specifically for where the[y] rest.

Good luck!

Thanks, NateDog.

If I understand you, the camshafts would normally be mated with the rebuilt head by the talkative machine shop guy. So I should give him the camshafts and the head from the junk yard.

Right??

Prices = Exhaust Manifold = $16; cam shafts = $15 each; cyl head = $40; valve cover = $5, so I am talking $91 out of $150 for the pieces supporting an off line rebuild of the head for later installation by another auto mechanic (not the machinist)

Barry sends

[rogermills]

Opps, sorry . . . Someone just told me that the head is on the other side of the engine....

Anybody want to go to the junk yard with me and hand me tools..

[[ humor intended ]]

Barry sends

[NateDogg]

HAHAHAHA that picture is priceless. is that you?? j/k..

Good luck at the junkyard.

[NISTECH]

Barry, Quit reading the service manual. Your egr run down made my head spin. The EGR does not richen anything as it is not adding fuel it is taking up the space of the fresh air in the intake since it lacks oxygen it wont burn as hot. The richening statment is idiotic engineering garble. It is a vaccum leak to the exhuast not fresh air. And perfect mixture is 14.7:1. That line your reffering to under the egr is the BPT pipe to the port under the BPT ,there should be a hose between that tube under the egr and the bottom port of the BPT. From the way you were talking, theres no hose there????