MB15 Posted April 10, 2012 Share Posted April 10, 2012 Hi guys , Just a wee question for ya's , Bought a manta gte exl hatch last week from a fellow member, (Cheap needing sum TLC ) I've replaced fuel tank , painted rear quarters , A General tidy up ect , Only problem left to fix is : between 1500 / 3000 rpm when driving in any gear she seams to Have a real bad hesitation , Are there any common problems to check for? Kev Quote Link to comment Share on other sites More sharing options...
tazz Posted April 10, 2012 Share Posted April 10, 2012 hi Kev had that same prob year or so back it ended up being a hair line crack in distributor cap. Andy Quote Link to comment Share on other sites More sharing options...
spiney_norman Posted April 10, 2012 Share Posted April 10, 2012 Distributor cap and plug leads would be the first things I'd check! Quote Link to comment Share on other sites More sharing options...
manta400john Posted April 10, 2012 Share Posted April 10, 2012 Maybe the track inside the air flow meter is worn where the arm moves across it ? Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 10, 2012 Author Share Posted April 10, 2012 (edited) Wee update , Had a quick look at her the day ,(lunch brake) Plugs and leads are new and getting a good spark , I've put on a new rotor arm and cap aswell but no diff Any other ideas to check? Things prone for going wrong on these ? She idles roughly and low revs she's quite rough/sluggish But above 3000/3500 she pulls clean , John - is it worth disconnecting the airflow meter? Anymore info boys Kev Edited April 25, 2012 by opeldvd11 Quote Link to comment Share on other sites More sharing options...
manta400john Posted April 10, 2012 Share Posted April 10, 2012 If you prise the top off carefully it should be clear to see if it's worn. Disconnecting it won't work . Quote Link to comment Share on other sites More sharing options...
Scribe of Lincoln Posted April 10, 2012 Share Posted April 10, 2012 You could try the fuel injection relay (mounted on the drivers inner wing), if you find that the airflow meter is OK. Quote Link to comment Share on other sites More sharing options...
mantasrme Posted April 11, 2012 Share Posted April 11, 2012 Depends what is causing the hessitation really, it could be lack of fuel/ too much air from a leak, too much fuel or the ignition timing not being right. All of these could be having a minor affect in the running of the engine across the whole rev range, but in the 1500-3000rpm range that small change is enough to loose power to a noticable amount as its taking the running of the engine further outside its ideal running setup than the rest of teh rev range The best way to identify the problem is on a rolling road where they will be able to monitor emmisions and ignition timing to see if its the fuel mix or ignition causing problems. Other than doing that i would have a check of the vac pipe to the dizzy which controls the igniton advance, if there's a split in it the ignition won't be changing as it should through the midrange. Other things that spring to mind are check the ignition timing itself and make sure there isn't a split pipe on the inlet system/ air leak around a gasket etc If none of those sow a problem i'd consider changing the airflow meter for another one and seeing if it makes a difference, the track inside that send the signal for how much air is going into the engine can wear and send a wobbly signal (my technical term) rather than a nice smooth increase as the airflow goes up. Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 11, 2012 Author Share Posted April 11, 2012 I`ll take a look boys , thank you for the info , Will let you no the outcome . . Kev Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 12, 2012 Author Share Posted April 12, 2012 If you prise the top off carefully it should be clear to see if it's worn. Disconnecting it won't work . Picture 5 - I`ve took the best picture here as i could , Is this too worn? Other things that spring to mind are check the ignition timing itself and make sure there isn't a split pipe on the inlet system/ air leak around a gasket etc I`ve checked all the air hose`s i can see and all seam to be okay , took the small pipe off the dizzy and checked it to , - no cracks , If the airflow meter is U/S Where would i get one ? any of you boys got a spare that i can buy to try out ? Kev Quote Link to comment Share on other sites More sharing options...
manta400john Posted April 13, 2012 Share Posted April 13, 2012 Looks ok from the picture. Is the flap smooth in operation. Think the issue may lie elsewhere? Quote Link to comment Share on other sites More sharing options...
mantadoc Posted April 13, 2012 Share Posted April 13, 2012 No warranty implied or given and no liability accepted. Ok Parts............... Distributor. A decent tech data book will give you the mechanical advance at 500 RPM increments so with a decent timing light that had a dial to adjust advance you can crank the car up in 500RPM intervals and check the advance curve. Vacuum advance needs disconnecting for this and you ideally need an accurate rev counter such as fitted to car mulyimeters not dashes. Vacuum advance is trickier to measure and I have seen threads on here where people disconnect the vacuum advance and plug the vacuum pipe to stop pinking so implies it can go soft on older cars. Injection Relay These tend to be unreliable but that is usually that when they fail pump doesn't run and car doesn't run. It won''t be this if car is fine at higher RPM when using more fuel. However, the 2P trick can be used to eliminate Plenum These very often work look and cause air leaks, if engine RPM changes when leaning on it or wobbling it then suspect an airleak and tighten / replace gaskets / fit modified washers under the bolts to sop it happeneing again as appropriate Throttle Switch These are actually a double pole switch, closed at idle it indicates to go to lean mixture, when closed at full throttle it indicates to go to richest mixture. Between closed and full open throttle it does nothing. Mine runs satisfactorily with it disconnected (not recommending it) and if correctly adjusted it is doing nothing at part throttle. Airflow Meter It will idle with this disconnected (not recommending it) but will stall as soon as throttle pressed. Marking alignment and then backing off the spring 5 notches allegedly improves pickup without adversley affecting economy. Allegedly...... If the lid has been off before and siliconed down someone may have done this but unless they marked original positin there is no easy way to tell if it has been tampered with and by how much Splits in the AFM pipe are common and I see your is taped up already, chck for splits near over tightened circlips. Shoo Goo is apparently the favoured repair material of Alfa owners (uses same LE Jetronic) The AFM is adjusted at the factory and should not be adjusted again. There should be an unbroken plastic plug in the sticky out bit by the end the elbow goes on. Generally test by substitution but hard to know the substitute is good unless your problem goes away. Just because it doesn't solve it doesn't mean it isn;t the issue. Auxiliary Air Valve If the car idles normally but revs once warm one of these sticking (pinch pipe flat to test) or splits in its pipes. Cold Start Valve When these fail cars are either hard to start or blue injector on back of plenum continues to fuel car making them over fuel. Usual test is to clamp the pipe off or disconnet the injector wire (plug will have brittle plastic below the spring clip) ECU I've never had a bad one yet but they do happen due to ingress of water from rotten foot wells. Worth a check and again test by substitution. Connections It is vital that the earth on the back of the plenum (below cold start injector) and the live that feeds the injection have good clean securely attached terminals, the live has a habit or working loose where crimped into the terminal. By the coil there is a green wire that feeds rev counter, it is also used to teed engine speed to ECU and trigger injectors. The male and female where it piggy backs into the coil can become iffy, although this usually causes a missfire or car to intermittantly die. What is the origin of the nut and bolt through the side of the AFM elbow? If not just a split repair it implies car has been messed with Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 13, 2012 Author Share Posted April 13, 2012 Mantadoc, There is a guy on ebay breaking a manta gte so ive emailed him for prices on a few parts, swap bits over ect - if they work in the first place! dizzy (compleate) airflow meter coil ecu inj relay. Injection Relay These tend to be unreliable but that is usually that when they fail pump doesn't run and car doesn't run. It won''t be this if car is fine at higher RPM when using more fuel. However, the 2P trick can be used to eliminate What and how do i do the 2p trick ? Plenum These very often work look and cause air leaks, if engine RPM changes when leaning on it or wobbling it then suspect an airleak and tighten / replace gaskets / fit modified washers under the bolts to sop it happeneing again as appropriate Whats the Plenum? Found this on ebay / Does the Plenum hold the injectors in? Airflow Meter It will idle with this disconnected (not recommending it) but will stall as soon as throttle pressed. Marking alignment and then backing off the spring 5 notches allegedly improves pickup without adversley affecting economy. Allegedly...... If the lid has been off before and siliconed down someone may have done this but unless they marked original positin there is no easy way to tell if it has been tampered with and by how much Splits in the AFM pipe are common and I see your is taped up already, check for splits near over tightened circlips. Shoo Goo is apparently the favoured repair material of Alfa owners (uses same LE Jetronic) The AFM is adjusted at the factory and should not be adjusted again. There should be an unbroken plastic plug in the sticky out bit by the end the elbow goes on. Generally test by substitution but hard to know the substitute is good unless your problem goes away. Just because it doesn't solve it doesn't mean it isn;t the issue. I really had to prise the top of the airflow box , dont think it had been opened before, Think it`s a case of swap over and try , Auxiliary Air Valve If the car idles normally but revs once warm one of these sticking (pinch pipe flat to test) or splits in its pipes. Is this it? Yeah seen the nut and bolt thru the afm hose , thats the prob - you dnt no what folk have been doing before you get an old car, Still need to check all the connections , Thanks for your time Kev Looks ok from the picture. Is the flap smooth in operation. Think the issue may lie elsewhere? I`d never been in about one before , Looked smooth but i`ll double check , Kev Quote Link to comment Share on other sites More sharing options...
mantadoc Posted April 13, 2012 Share Posted April 13, 2012 Mantadoc, There is a guy on ebay breaking a manta gte so ive emailed him for prices on a few parts, swap bits over ect - if they work in the first place! dizzy (compleate) airflow meter coil ecu inj relay. Get Shug to post you my loan set of distributor, coil and amp etc. - Note this is to test, not to keep and not selling it and you post it back to me at your own expense. Once you work out if one of your parts is dodgy by substitution my parts come back to me. Yo getting more parts if required remainds your problem. It may be my only spare dizzy so if I don't get it back I will be not happy. Injection Relay These tend to be unreliable but that is usually that when they fail pump doesn't run and car doesn't run. It won''t be this if car is fine at higher RPM when using more fuel. However, the 2P trick can be used to eliminate What and how do i do the 2p trick ? Use the search box with the following in including quotes "2p trick" and you will find it in one of the threads Plenum These very often work look and cause air leaks, if engine RPM changes when leaning on it or wobbling it then suspect an airleak and tighten / replace gaskets / fit modified washers under the bolts to sop it happeneing again as appropriate Whats the Plenum? The really large piece of aluminium above the exhaust that all the injection bits hang off Found this on ebay / Does the Plenum hold the injectors in? Airflow Meter It will idle with this disconnected (not recommending it) but will stall as soon as throttle pressed. Marking alignment and then backing off the spring 5 notches allegedly improves pickup without adversley affecting economy. Allegedly...... If the lid has been off before and siliconed down someone may have done this but unless they marked original positin there is no easy way to tell if it has been tampered with and by how much Splits in the AFM pipe are common and I see your is taped up already, check for splits near over tightened circlips. Shoo Goo is apparently the favoured repair material of Alfa owners (uses same LE Jetronic) The AFM is adjusted at the factory and should not be adjusted again. There should be an unbroken plastic plug in the sticky out bit by the end the elbow goes on. Generally test by substitution but hard to know the substitute is good unless your problem goes away. Just because it doesn't solve it doesn't mean it isn;t the issue. I really had to prise the top of the airflow box , dont think it had been opened before, You're probably right Think it`s a case of swap over and try , Auxiliary Air Valve If the car idles normally but revs once warm one of these sticking (pinch pipe flat to test) or splits in its pipes. Is this it? If you mean the round thing above the thermostat housing with the small pipe from the AFM elbow to it then yes Yeah seen the nut and bolt thru the afm hose , thats the prob - you dnt no what folk have been doing before you get an old car, Still need to check all the connections , Thanks for your time Kev I`d never been in about one before , Looked smooth but i`ll double check , Kev Have you static timed it or used a timing light and maybe checked the cam timing. Thinking about it i'm not 100% sure yo have an issue, snapping the throttle open at low RPM frops airspeed and basically kills the vacuum momenterily. Not sure I would expect a 20 year old car that left the factory with 110 horses to be sparkling. Of course I can't see what you see so it does obviously depend on wat oyu are experiencing Quote Link to comment Share on other sites More sharing options...
dog321fish Posted April 14, 2012 Share Posted April 14, 2012 On the photo above, you look to have a split/crack just above the jubilee clip where the AAV pipe connects to the AFM elbow? HTH Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 14, 2012 Author Share Posted April 14, 2012 On the photo above, you look to have a split/crack just above the jubilee clip where the AAV pipe connects to the AFM elbow? HTH Yeah it looks like it`s split but on the inside it`s not if you get me , Mantadoc I`ve PM`d you Kev Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 15, 2012 Author Share Posted April 15, 2012 Just back from buying a rotten manta gte hatch for parts to swap over ect Kev Quote Link to comment Share on other sites More sharing options...
monzta Posted April 16, 2012 Share Posted April 16, 2012 Hi Kev. Really the flaw can lie almost anywhere. The best way to do this is to use the rule of elimination and write down what you change. As it is only a problem at lower revs i will suspect false air to be the sinner. There are loads of places where this can happen, but most of it is a cheap repair / fix and should be attempted first. Your intake manifold head gasket should be checked. Your injectors gaskets should be checked. Your brake servo air hose should be checked. There are other vacum controlled units on your injection system (like the fuel shut-off-valve). Are all vacum hoses on the intake manifold 100% ok`? Check your spark plugs. They tell alot about the engine too. If they are all black (and maybe even wet) you have to rich a mixture and then maybe an adjustment of the fuelregulator can do the trick? If they are all light brown the mixture is too lean (see above regarding false air). If the spark plugs look like they should you may have electrical problems with the ignition. Have you checked the ignition module located beneath the coil ? This unit has a tendency to die after some time, and they can really be a problem. Usually they just go dead, but sometimes they can make everything run really bad.. Hope you get it sorted Best regards, Ruben Quote Link to comment Share on other sites More sharing options...
mantadoc Posted April 16, 2012 Share Posted April 16, 2012 If they are all black (and maybe even wet) you have to rich a mixture and then maybe an adjustment of the fuelregulator can do the trick? The colour of plugs is only a guide if they are correctly adjusted AND the correct grade. There is no reliable way to adjust the standard fuel pressure regulator. Most common mistakes with the fuel regulator are missing or damaged vacuum pipe and the ever popular puttin the fuel feed to it rather than it being Teed into the return line Quote Link to comment Share on other sites More sharing options...
monzta Posted April 16, 2012 Share Posted April 16, 2012 (edited) That is not my experience. Yes if they are wrong for the engine that would be a good place to find the flaw. No plug will function at its optimal if its not right for the engine. Exactly my point its a guide that can direct you in 3 different paths when searching for flaws on the engine. Ignition / electrical stuff, rich mixture, lean mixture. The tales that the sparkplugs tell are not lies. The fuel regulator can misfunction letting the full amount of fuel (or less) that the pump can deliver reach the injectors, the injectors can also get stuck in open position like the cold starter injector can be open all the time. All of these flaws are rich-fuel related. However, i would say that its more than likely that its a electrical thing, or lean mixture due to a leak somewhere (gaskets, hoses etc) Edited April 16, 2012 by monzta Quote Link to comment Share on other sites More sharing options...
MB15 Posted April 18, 2012 Author Share Posted April 18, 2012 Well that`s the "New" Manta home lol , Nice one from a farm for spares , (Just need time now to see whats good) Front Recaros are or will be mint with a good clean, Kev Quote Link to comment Share on other sites More sharing options...
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