m20 starts then dies

[steve_k]

evening folks back with another problem.

start from the beginning,

engine in question is a m20 2.7 stroker (rebuilt hartge h27 lump), recently had a problem were when i started the engine the revs would go straight to 3000rpm, turned out to be the throttle cable in the wrong clip on the TB, keeping the throttle open, all sorted now though.

now on the next problem, when i start the engine the revs shoot up (as expected) then when they drop down it cuts out & dies,

i've checked for fuel & spark, both present, timing is spot on, checked & cleaned the ICV it's buzzing when the ignition is turned on,

my thinking is maybe the ecu has "lost" the idle settings??

if it has how would i go about setting the idle again?

does anyone have any ideas as to what could causing it to cut out/die instead of catching the idle??

hopefully i can get it sorted by the weekend as the mot is booked for then & i really need the car on the road.

[steve_k]

bump, bttt

[steve_k]

Afternoon folks, well following on from my post yesterday about the fact my 2.7 m20 will start then die/shut off & following the comments about it I have checked for air/vacuum leaks & there are none as the gaskets are new the inlet elbow & icv pipes are new silicone ones.

All the other hoses at the TB are new.

I removed the TB from the car, checked for the "click" when the throttle is just off its stop & I can hear the"click".

Also I tested the TPS for both resistance & continuity & the switch has passed on both counts,

Checked the flap in the afm & that moves freely & not binding, cleaned & checked the icv (buzzes with the ignition turn on).

So I'm now scratching my head as to what could be causing the engine to die/shut off after starting.

Anyone got any more ideas as to what the issue could be??

So I'm now left scratching my head

[paultv]

Long shot, is your fuel pressure good?

Normally more air getting in makes for a high idle, not shutting down.

Have you tried setting a manual idle, in other words remove the icv pipe and block it up so no air can get into the throttle body through the icv feed and start the car, can you get a steady although maybe high idle using the tps set screw? If you can it points to the icv, if not maybe you have fuel starvation,

What's been done since it last ran correctly?

Paul

[arrisbmw]

Long shot, is your fuel pressure good?

Normally more air getting in makes for a high idle, not shutting down.

Have you tried setting a manual idle, in other words remove the icv pipe and block it up so no air can get into the throttle body through the icv feed and start the car, can you get a steady although maybe high idle using the tps set screw? If you can it points to the icv, if not maybe you have fuel starvation,

What's been done since it last ran correctly?

Paul thats a good check, but if you turn the set screw too far in, it will increase the idle by opening the throttle body butterfly but in doing so . it will screw up the correctly set tps. eand tell the ecu the car is off idle , which its not.
https://www.e30zone.net/e30wiki/index.p ... ion_Switch

[steve_k]

Long shot, is your fuel pressure good?

Normally more air getting in makes for a high idle, not shutting down.

Have you tried setting a manual idle, in other words remove the icv pipe and block it up so no air can get into the throttle body through the icv feed and start the car, can you get a steady although maybe high idle using the tps set screw? If you can it points to the icv, if not maybe you have fuel starvation,

What's been done since it last ran correctly?

Paul

paul, thanks for the reply,

i will try what you recommend about setting a manual idle tomorrow,
fuel pressure seems to be fine. can't find any air leaks on the inlet side (all hoses/pipes are silicone from samco).

as for whats been done to the car since it was last ran correctly? it has had the h27 (2.7) lump fitted which ran fine before it was fitting in my car, & it ran fine before i laid the car up to sort some bodywork issues & fit a rebuilt head,

thats whats got me so stuck on whats gone wrong.

[steve_k]

arrisbmw, if i was to adjust the TPS screw i would mark it to show where it was before i moved it.

[arrisbmw]

only trying to help. on my m40 icv its got an adjuster set screw . which is factory set . needs a lot of clearing out of clear stuff if you want to adjust it,. iirc it a small allan key grab screw, which i don,t think your suppose to adjust, but when you do it does change the idle speed up and down.
dont know if its on yours and depends accessibility of the i,c,v. i just bought a second hand one to have a play.

[arrisbmw]

could be something stupid like plugs, leads , or dizzy cap dirty inside, rotor.

[steve_k]

arris, i cleaned the icv the other day but will check it & clean it again if need be,
the only screw i can find on the TB is the one on top next to the throttle arm, can't get that to move at all,

checked the TPS & that is fine, clicks when it should.

will check both the dizzy cap & rotor arm again just to be sure,

might sound extreme but if need be i'll try to set the idle manually like paul says but pin the throttle open a little bit & see if that works,

doing my box in as i need the car back on the road by the end of next week,

[arrisbmw]

no you miss understood me the grub screw is in the body of the idle control valve. your probably have to remove the icv to see it. on mine was covered in clear glue like stuff. you said tps clicks when it should did you check it with a multimeter as the guide says on wiki on here. see below

To test the TPS, remove its plug and connect a resistance meter to pins 1 and 2. You should get a short circuit ( 0 Ohms) with the throttle closed, going open circuit with the throttle just off its stop. Pins 1 and 3 should be open circuit until the throttle is 2/3 open, when it should go short circuit. If you are not getting these readings, remove and clean the TPS.

Removing and cleaning a TPS is easy, and should be cleaned with Contact Cleaner. It can also be good to drill a 1- or 2mm hole right into the middle of the TPS as well, which will allow oil from the Throttle Body to drain out without blocking the TPS in future.

[steve_k]

Arris, I've checked the icv & for the life of me I can't find a screw on there, the body of it has a black rubber like sheath/cover with only the inlet/outlet pipes exposed (its the later T shape one) & has the connector (3 pin) on the other end.

Cleaned it out with carb cleaner & cleaned the plug end with electrical contact cleaner. When it's plugged in & the key in the "on" position you can hear/feel it buzz.

As for the TPS, cleaned up the 3 pin connections, tested it with a multi meter,

Checked for both resistance (ohms) and continuity (beep test) & it passes on both tests,

I can hear the "click" as the throttle is moved just off its stop and again when it's closed.

Today I adjusted the throttle cable to remove any slack (there was a bit) put everything bck together & went to start the car,

Got it fired up, the revs climbed to 1500rpm, then down to about 600 where sounded like it was going to stall then they shout up to 3k rpms where it stayed till I shut the engine off.

I really am at a loss as to what it could be
I simply don't have a clue what else to do.

[arrisbmw]

oh sorry to hear that. sounds like your back to square one. I have a bit of slack in the t cable. have you tried a different icv.
what happens if you unplug the icv. ? mine runs fast about 1100 rpm but the car dont seem to drive right once its warm.

if you just wanna drive the car temp . do a icv delete. by somehow blocking the rubber hose that goes from the rubber boot to the icv, then put it all back together and adjust the idle stop screw. what ever you use to block the hose be aware you don,t want it getting into the engine. and causing damage. your shout !! i,d probably use a rubber bung the same size as internal of pipe. if you can,t clamp it off from the outside . with those brake pipe clamps. it could be a problem with the wiring to the i.c.v. short somewhere. or broken wire.

[steve_k]

Thanks arris,

Not tried pulling the plug on the icv yet.
Can't drive the car at the moment mainly because of this problem & no mot.

Has a search on here & found a post about a similar problem.
It said that if the battery is flat/off for a while the ecu "loses/forgets" it's (idle) settings & that it will run rough & idle very high (3k?) for a while as it relearn's its settings.

Makes me wonder if that could be the problem as the battery was of for ages while I did the engine rebuild.

Thing is would it be safe to leave it at 3000rpm for about 10mins while the ecu sorts itself out??

[arrisbmw]

Thing is would it be safe to leave it at 3000rpm for about 10mins while the ecu sorts itself out??

your call . not ideal on a coldengine.

i don,t thinks thats true. I just fitted a different ecu ( same part number ) into my car dont know how long it been disconnected for weeks months. idle still 600 -700 rpm.
I personally think you got a faulty i.c.v or wiring issue, or butterfly open slightly on t.b or unmetered air getting in.

[steve_k]

Thing is would it be safe to leave it at 3000rpm for about 10mins while the ecu sorts itself out??

your call . not ideal on a coldengine.

i don,t thinks thats true. I just fitted a different ecu ( same part number ) into my car dont know how long it been disconnected for weeks months. idle still 600 -700 rpm.
I personally think you got a faulty i.c.v or wiring issue, or butterfly open slightly on t.b or unmetered air getting in.

i'm starting to lean towards an air leak/unmetered air getting in, will have a look at the TB & see if it's closing fully or not.

[davidt]

This sounds like the ECU needs to relearn the idle, on my car if I disconnect/reconnect the battery the idle will in be high then will try to stall. I will have to drive for about twenty miles then all is good, try to hold the throttle open for long enough to warm the engine. my car is a face lift model but friends with pre face lift cars don't have this problem maybe its the ECU version.

[steve_k]

cheers davidt, can't take it for a run just yet as there's no mot,

just checked the ICV & AFM & blur temp sensor.

not getting any resistance reading on the blue temp sensor at all, nill, zero, nothing.

on the ICV i'm getting a reading of 20 ohms between pins 1 & 2, 18 between 2 & 3 & 38 between 1 & 3, is this normal or not?

also the AFM, getting 38.5 ONLY between pins 1 & 3, zero from the rest.

so from that does any have an idea?

[steve_k]

Forgot to add,

I will retest the afm tomorrow as I didn't check the resistance while moving the flap,

Will see what results I get back from that.

[davidt]

You should have a reading from the CTS, I had a look in the American Bentley Manual and it shows test temperatures and resistance ohms for the blue sensor. -10 C 8200-10500, 20 C 2200-2700, 80 C 300-360. also something I noticed in the Manual was the metal/plastic 2 wire ICV with external adjusting screw maybe north American only.

[steve_k]

You should have a reading from the CTS, I had a look in the American Bentley Manual and it shows test temperatures and resistance ohms for the blue sensor. -10 C 8200-10500, 20 C 2200-2700, 80 C 300-360. also something I noticed in the Manual was the metal/plastic 2 wire ICV with external adjusting screw maybe north American only.

I've got the Bentley manual on the PC so will have look in there as well.

But like I say I'm getting a zero reading from the cts, so just in case I've got a bosch one on the way, makes me wonder but I doubt that alone would cause the engine to either shut off straight away or idle at 3K,

Also got a new tps on the way as well.

As for the icv I've never seen a uk/eu e30 with an adjustment screw on them. The only screw I've found in that area is the one on top of the tb for the throttle stop & that won't budge as its never been moved.

Really am stumped with this.

[steve_k]

Update.

To rule out a broken wire to either the AFM/TPS/ICV I used a test light,

Turned the ignition on & in turn checked the connectors to all 3 mentioned above & found they were all getting power.

Also checked the resistance on the AFM as the flap was slowly opened, had resistance all the way (can't remember if it was up or down) so I'm sure that is working as it should.

Also noticed that when I open the throttle there is a click as it comes off the stop but none as it hits WOT & I'm sure there's meant to be??

I really don't know what or where else to check.

I'm at my wits end with no transport till this is sorted.

[shedrool83]

Have you looked at cps?

[steve_k]

Have you looked at cps?

Yep, replaced that with a brand new one as the old one was past it's best.

[paultv]

One place that air can get in that is often overlooked - there's a rubber "stopper" located underneath the inlet manifold behind the Throttle valve switch or TPS.

Here's a shot of it - is yours missing or split allowing air in??

[steve_k]

it's there but i will have to check the condition of it.

[Topblag]

I've seen this before, I think. The fuel filter was on the wrong way round....

[steve_k]

I've seen this before, I think. The fuel filter was on the wrong way round....

i'll check, but i'm sure it ain't.

[steve_k]

well i#ve been out & checked the fuel filter, yes it's on the correct way, i've checked/cleaned/tested/rechecked all the electric parts on the inlet side, checked for air/vacuum leaks (none round).

searched this forum * others countless times yet still can't find anything.

i really am at a standstill with this now, got no transport either because of this, so close to phoning the scrap yard, all the work thats gone into the engine rebuild, bodywork etc looks to have been all for nothing

[flybynite]

Steve, feel for you mate, banging head against brick walls with cars is something we have all done far too often.

Had an engine change in an Escort RS that would not start, running car, running engine tried everything for weeks. Turned out a baffle in a good exhaust had come lose during the change and blocked the exhaust. Only found it when we forgot to connect the down pipe on one try and it ran

From what you have ruled out (vacuum and idle control problems), can't help feeling it is fuel. The fuel filter thing mentioned above rings true but a restriction or blockage in the fuel lines can do strange things.

What are the plugs like when you take them out just after running a short time? are they coked, lean, wet or dry?

Also check anything new you have fitted during this swap. Might be new but doesn't mean it works.

[steve_k]

Steve, feel for you mate, banging head against brick walls with cars is something we have all done far too often.

Had an engine change in an Escort RS that would not start, running car, running engine tried everything for weeks. Turned out a baffle in a good exhaust had come lose during the change and blocked the exhaust. Only found it when we forgot to connect the down pipe on one try and it ran

From what you have ruled out (vacuum and idle control problems), can't help feeling it is fuel. The fuel filter thing mentioned above rings true but a restriction or blockage in the fuel lines can do strange things.

What are the plugs like when you take them out just after running a short time? are they coked, lean, wet or dry?

Also check anything new you have fitted during this swap. Might be new but doesn't mean it works.

Thanks dude, really struggling,

Checked the plugs (brand new the other week) slightly soothed up which I put down to the fact there was a fuel like when I first tried to start it.

The only "new" part was a refurbished afm as the old one was past it & I had a new one to hand.

Also, got a new TPS on the way as the current one only clicks very slightly.

[martauto]

Hello Brian, one for you mate !

Mart.

[paultv]

Did you disconnect the ICV then block both the tubes - one into the rubber boot and the other into the throttle body, then try to start, if it won't and you want to open the throttle a little without fiddling with the TPS screw, just tighten up the throttle cable a little. with the nylon nut - you should be able to obtain a good but slightly high idle when doing this.

If it does start and races - you have to have air getting in somewhere - or jammed open AFM. there's nowhere else for air to get in if it's all good - did you check the vacuum feed to the servo? take it off as well and block it good - you may have a servo leak.

Paul

[steve_k]

Did you disconnect the ICV then block both the tubes - one into the rubber boot and the other into the throttle body, then try to start, if it won't and you want to open the throttle a little without fiddling with the TPS screw, just tighten up the throttle cable a little. with the nylon nut - you should be able to obtain a good but slightly high idle when doing this.

If it does start and races - you have to have air getting in somewhere - or jammed open AFM. there's nowhere else for air to get in if it's all good - did you check the vacuum feed to the servo? take it off as well and block it good - you may have a servo leak.

Paul

hi paul, not had chance to try that with the ICV just yet, will try in the next day or so (hospital appointment tomorrow so will try tuesday), the idea with the throttle cable might b easier for me as the tps screw is stuck solid,

as for the afm, as i said above it's a refurbished one, & i know the flap is moving freely & not stuck, also i'll check/try the vacuum feed to the servo.

[Brianmoooore]

now on the next problem, when i start the engine the revs shoot up (as expected) then when they drop down it cuts out & dies,

What happens if you apply throttle with your foot before the revs drop off and it dies?