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Car Forum / Saab Cars / May 2005Replaced my DI cassette. Now getting misfire on 4... Help!
Long story short: Card died on the highway, I replaced my ID cassette, used properly gapped NGK Resistor plugs. It now runs but no turbo boost. Engine light comes on and the DTCs (P0304 & P1304) indicate misfire on 4. So I took apart the old DI cassette and what do you know? The cylinder 4 coil was covered in oil and there was actually a cracked buldge next to it in the housing. Any ideas? ... at all? I'm lost. Thanks very much, John Hooven > Long story short: Card died on the highway, I replaced my ID >cassette, used properly gapped NGK Resistor plugs. It now runs but no [quoted text clipped - 7 lines] >Thanks very much, >John Hooven Most likely the new cassette was duff. Send it back for a replacement. I assume it's not too obvious that you've had it apart? Cheers, Colin. > > Long story short: Card died on the highway, I replaced my ID > >cassette, used properly gapped NGK Resistor plugs. It now runs but no [quoted text clipped - 14 lines] > > Colin. I don't think it's the cassette. I took the OLD cassette apart and the Cyl. 4 coil was gone. With the new cassette in, the DTCs report misfire on Cyl 4. So I figure somthing (Trionic?) caused cyl. 4 to misfire and that is what caused the cassette to go in the first place. I have a local independant Saab mechanic who comes highly recomended. I guess I'll have it towed to his place. :-( Thanks, John Hooven >> > Long story short: Card died on the highway, I replaced my ID >> >cassette, used properly gapped NGK Resistor plugs. It now runs but [quoted text clipped - 23 lines] > I have a local independant Saab mechanic who comes highly >recomended. I guess I'll have it towed to his place. :-( Oh, I see. I thought you'd taken the new one apart. Doh! In that case, Maybe you were unlucky enough to have the old one blast the ECU as it failed. The dumbed-down diagram in the manual makes it look like the ECU outputs directly drive thyristors in the DI cassette without any buffering, so if one of those failed, it could have sent 400V back up the ECUs output. I'd say you're right. It's time to admit defeat and get the car looked at by someone with a box of bits to swap in and out to pin down the problem. Incidentally, does the car feel like it's mis-firing when off-boost? If the ECU output is knackered, number 4 would never fire, so it would be quite noticeable. Cheers, Colin. No, it idles fine. When I put the accelerator to the floor, it only reaches < 4000rpm and starts to buck. What is the ECU? Thanks again, John Hooven > No, it idles fine. When I put the accelerator to the floor, it >only reaches < 4000rpm and starts to buck. > What is the ECU? That'd be the Engine Control Unit which is an essential part of the engine management system for almost any modern engine due to the super-tight tolerances on emission control, fuel usage, etc. I like Saab's 8V engines because they don't need any ECU, but the flipside is they're nowhere near as high-performing and less efficient overall. I like the reliability but 16V engines and later designs have a lot of good points which the older engines didn't have. Regards, Craig.  SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Saab C900 Workshop -- For all Saab C900 Enthusiasts world-wide! http://www.saab900classic.net http://www.saab900.org c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. > No, it idles fine. When I put the accelerator to the floor, it >only reaches < 4000rpm and starts to buck. Yep. That'll be the limp-home mode because the ECU thinks there's a miss-fire. It's still a bit of an unknown whether the miss-fire is real or not. > What is the ECU? "Engine Control Unit". In your case (I think) the Main Trionic control module. If you have a scope, you could check for the trigger pulses on pins 2,3,4 and 5 of the DI cassette. Pin 5 is the suspect one. Here's the diagram from the manual, if it's any help. http://www.stamp.plus.com/temp/SaabIgnition.gif Cheers, Colin. Well I tried disconnecting the bat for around 5 minutes. No change. Thanks for the pin-out that helps. I'll check pin 5 (assuming I can find my scope :-) as soon as it stops raining. Thanks again to all for your help, John Hooven > Well I tried disconnecting the bat for around 5 minutes. No change. > Thanks for the pin-out that helps. I'll check pin 5 (assuming I can > find my scope :-) as soon as it stops raining. > > Thanks again to all for your help, > John Hooven But even this might not clear the ECU diagnostics (if this is the problem). The important thing to look for is whether the problem gets better or worse after several starts, as the ECU gradually returns to normal. [...] > I don't think it's the cassette. I took the OLD cassette apart and > the Cyl. 4 coil was gone. With the new cassette in, the DTCs report [quoted text clipped - 5 lines] > Thanks, > John Hooven It may be that the condition of the old DI is still registered on the ECU and it need to be cleared. If this is the case, then the condition should improve after several engine starts. The ECU should be the last to suspect; it is (1) well shielded and doesn't 'wear and tear', and (2) it's very expensive. yeah all u need to do is disconnect the battery for like 5min and reconnect it the ecu will reset everything. > yeah all u need to do is disconnect the battery for like 5min and > reconnect it the ecu will reset everything. If you disconnetc the battery, remember that you should only disconnect the ground cable, not the + (plus) wire. Cheers! >>yeah all u need to do is disconnect the battery for like 5min and >>reconnect it the ecu will reset everything. [quoted text clipped - 3 lines] > > Cheers! Why? -Fred W >>>yeah all u need to do is disconnect the battery for like 5min and >>>reconnect it the ecu will reset everything. [quoted text clipped - 5 lines] > >Why? I've always thought of it as good practice ever since I nearly welded a spanner to the engine of an Austin Allegro in my younger days... Cheers, Colin. >>>>yeah all u need to do is disconnect the battery for like 5min and >>>>reconnect it the ecu will reset everything. >>> If you disconnetc the battery, remember that you should only disconnect the >>> ground cable, not the + (plus) wire. >>Why? > I've always thought of it as good practice ever since I nearly welded > a spanner to the engine of an Austin Allegro in my younger days... Ah, so he's saying disconnect ground _first_, not "don't disconnect + ever", then? >>>>>yeah all u need to do is disconnect the battery for like 5min and >>>>>reconnect it the ecu will reset everything. [quoted text clipped - 9 lines] >Ah, so he's saying disconnect ground _first_, not "don't disconnect + >ever", then? Yep. I reckon the word "only" must have crept in there by mistake. Otherwise you'd have a hell of a job replacing the battery ;o). Cheers, Colin. >>>> If you disconnetc the battery, remember that you should only disconnect >>>> the >>>> ground cable, not the + (plus) wire. > >>>Why? Besides burns, you can fry the electronic boxes in the car... > Ah, so he's saying disconnect ground _first_, not "don't disconnect + > ever", then? Yep. :o) Cheers! >>>>yeah all u need to do is disconnect the battery for like 5min and >>>>reconnect it the ecu will reset everything. [quoted text clipped - 8 lines] > I've always thought of it as good practice ever since I nearly welded > a spanner to the engine of an Austin Allegro in my younger days... Sorry, I should have been more specific. I agree, you should disconnect the battery. But why *only* the negative (ground) cable? You could do both. I think you meant that you should always disconnect the negative *first* for safety reasons. -Fred W >>>yeah all u need to do is disconnect the battery for like 5min and >>>reconnect it the ecu will reset everything. [quoted text clipped - 7 lines] > > -Fred W It's a safety procedure, touch the bodywork/engine etc of a negative earthed car whilst (stupidly) touching the metalwork/contact of the positive terminal will cause a short, which can give you a nasty jump and even a burn. Advertised on motor mechanic courses here with photos of burns to wrists of guys who contacted with a metal wristwatch band. Disconnect the negative and touch the body/engine at the same time it doesn't matter. Other than the above safe working procedure Fred, you are spot on, a circuit is a circuit and you break it whichever side of the power source you disconnect. Al P.S. Is "like 5min" another way of saying five minutes, or does he mean 4 minutes and 59 seconds, which is similar but not the same? So therefore could be described as like. ;-) > P.S. Is "like 5min" another way of saying five minutes, or does he mean 4 > minutes and 59 seconds, which is similar but not the same? So therefore > could be described as like. ;-) He's saying: At least 5 minutes. I usually make it 15... Cheers! > It's a safety procedure, touch the bodywork/engine etc of a negative earthed > car whilst (stupidly) touching the metalwork/contact of the positive [quoted text clipped - 4 lines] > Disconnect the negative and touch the body/engine at the same time it > doesn't matter. Actually, I knew where he was going, but it was the "only" the negative which I wanted him to clarify. Also, just touching those with your body even with a wristwatch on will not cause one bit of a problem. The resistance of your body / skin is high enough that a 12v source will not even cause you a tingle. This is one of the reasons they stick with the inefficiencies of low voltage in auto and marine applications. But, swing a wrench around and contact some grounded metal while disconnecting the positive lead (with the negative one still connected) and watch the sparks fly. > P.S. Is "like 5min" another way of saying five minutes, or does he mean 4 > minutes and 59 seconds, which is similar but not the same? So therefore > could be described as like. ;-) Yes, "like 5 min" is 'merican slang for "approximately 5 minutes or so, old chap", but like, I didn't say that man... It was some other dude. ;-) -Fred W >> It's a safety procedure, touch the bodywork/engine etc of a negative >> earthed car whilst (stupidly) touching the metalwork/contact of the [quoted text clipped - 27 lines] > > -Fred W Cor blimey guvnor! bit posh aint'cha? Old bean he says! Seriously, I was taking the Mick. Hence the emoticon, I just find it a bit odd sometimes when people write in the same manner they would speak. Don't get me wrong, I'm from good old Blighty, and I certainly don't have a great grasp of written English! After all I never used to be able to spell Engineer, now I is one..... Regarding +ve/-ve order, sorry but I cannot agree on the low voltage not causing you any harm. Given the right conditions you can actually get a nasty jump off a good battery, and yes, even a burn. It is after all the amps that get you. I also forgot to mention possible petrol ignition from the ensuing spark. Anyway it's academic really as you were of course only questioning the "only" bit of the statement. Cheers Al >>>It's a safety procedure, touch the bodywork/engine etc of a negative >>>earthed car whilst (stupidly) touching the metalwork/contact of the [quoted text clipped - 32 lines] > Seriously, I was taking the Mick. Hence the emoticon, I just find it a bit > odd sometimes when people write in the same manner they would speak. Ditto. > Don't get me wrong, I'm from good old Blighty, and I certainly don't have a > great grasp of written English! After all I never used to be able to spell > Engineer, now I is one..... Ditto ditto. > Regarding +ve/-ve order, sorry but I cannot agree on the low voltage not > causing you any harm. Given the right conditions you can actually get a > nasty jump off a good battery, and yes, even a burn. It is after all the > amps that get you. I also forgot to mention possible petrol ignition from > the ensuing spark. Amps yes, but if you're an injuneer (as I am), you'll already know that you don't get many amps without either lots of volts or little resistance. In this case we have neither; Low volts (12) and lots of resistance (skin). In fact, you won't even be able to draw a spark so no gas vapor explosion either. All of this is true *until* you lower the resistance of the contacts somehow... > Anyway it's academic really as you were of course only questioning the > "only" bit of the statement. Right, you are... -Fred W > >> It's a safety procedure, touch the bodywork/engine etc of a negative > >> earthed car whilst (stupidly) touching the metalwork/contact of the [quoted text clipped - 49 lines] > > Al In the UK, unlike Germany, the term 'engineer' is often misused by the likes of gas fitters, washing machine mechanics, etc. We end up with so called engineers and professional engineers. The latter being a rarer group. [...] > In the UK, unlike Germany, the term 'engineer' is often misused by the likes > of gas fitters, washing machine mechanics, etc. We end up with so called > engineers and professional engineers. The latter being a rarer group. This is very true. However, people in UK know the difference. It is not a debasement of the engineering profession; rather they are trying to be polite. It is almost the same phenomenon as in other contexts, when the same word is used for different meanings. E.g. 'Doctor' is commonly used for someone with a medical qualification, not necessarily an PhD or an MD. > [...] >> In the UK, unlike Germany, the term 'engineer' is often misused by the [quoted text clipped - 8 lines] > used for someone with a medical qualification, not necessarily an PhD or > an MD. Yup, I am a Civil Engineer, I'm not chartered due to kids/work lack of application, but I am an experienced Member (Graduate) of The Institution of Civil Engineers. There are some members who seem to get quite upset over television engineers and photocopier engineers. Others are quite content and don't let it get them down. As far as I'm concerned anyone who can design, build or fix something technical is an engineer even without the relevant paperwork/certificate. As one of my clients once said, " I don't need an engineer with certificates, I need one who knows how to fix the Landrover in the middle of the dessert with only a teaspoon and a piece of string" When I talked about the right conditions somewhere above, I was referring to a damp/sweaty oily set of arms/fingers/wrenches etc coming into contact with the wrong bits. Thus your resistance is lowered. However, being a Civil Engineer I am more knowledgeable on Concrete (which also burns!) and steel than electrical circuits. Although I do have some rudimentary knowledge. As stated earlier, it's academic but hey at least we're all talking. Al >> This is very true. However, people in UK know the difference. It is not >> a debasement of the engineering profession; rather they are trying to >> be polite. It is almost the same phenomenon as in other contexts, when >> the same word is used for different meanings. E.g. 'Doctor' is commonly >> used for someone with a medical qualification, not necessarily an PhD or >> an MD. > There are some members who seem to get quite upset over television engineers > and photocopier engineers. Others are quite content and don't let it get > them down. As far as I'm concerned anyone who can design, build or fix > something technical is an engineer even without the relevant > paperwork/certificate. My title is "Unix systems architect", says so on the business card and my job description. I had one particular person who was a building-architect go ballistic, literally red in the face and jumping up and down, that "that's not a real architect and yadda yadda yadda". Being the person of ultimate tact and diplomacy that you all know me to be, I suggested that words evolve and that he should get over it. > As one of my clients once said, " I don't need an engineer with > certificates, I need one who knows how to fix the Landrover in the middle of > the dessert with only a teaspoon and a piece of string" Hate it when my vehicle breaks in the middle of dessert. At least it waited until the main course was over. > When I talked about the right conditions somewhere above, I was referring to > a damp/sweaty oily set of arms/fingers/wrenches etc coming into contact with > the wrong bits. Thus your resistance is lowered. So standing on a sponge soaked in salt water is a bad practice then? Who knew?!?!?!? > However, being a Civil Engineer I am more knowledgeable on Concrete (which > also burns!) and steel than electrical circuits. Although I do have some > rudimentary knowledge. > As stated earlier, it's academic but hey at least we're all talking. My lips haven't moved a bit, actually... > My title is "Unix systems architect", says so on the business card and > my job description. I had one particular person who was a > building-architect go ballistic, literally red in the face and jumping > up and down, that "that's not a real architect and yadda yadda yadda". > Being the person of ultimate tact and diplomacy that you all know me to > be, I suggested that words evolve and that he should get over it. Should have asked him to draw up a Unix System for you then, Dave. >>As one of my clients once said, " I don't need an engineer with >>certificates, I need one who knows how to fix the Landrover in the middle of >>the dessert with only a teaspoon and a piece of string" > > Hate it when my vehicle breaks in the middle of dessert. At least it > waited until the main course was over. Make mine pie, thanks. >>When I talked about the right conditions somewhere above, I was referring to >>a damp/sweaty oily set of arms/fingers/wrenches etc coming into contact with >>the wrong bits. Thus your resistance is lowered. > > So standing on a sponge soaked in salt water is a bad practice then? > Who knew?!?!?!? Is this before or after pie? Mmmmm, pie... I thought the sponge was outlawed? >>However, being a Civil Engineer I am more knowledgeable on Concrete (which >>also burns!) and steel than electrical circuits. Although I do have some [quoted text clipped - 3 lines] > > My lips haven't moved a bit, actually... Mine always do when I type. Bad habit, I suppose. So, my take-aways are to never touch a car battery before (or is it after) having pie or if on the sponge. ;-) -Fred W Ya know, I learn something new every day... >> My title is "Unix systems architect", says so on the business card and >> my job description. I had one particular person who was a >> building-architect go ballistic, literally red in the face and jumping >> up and down, that "that's not a real architect and yadda yadda yadda". >> Being the person of ultimate tact and diplomacy that you all know me to >> be, I suggested that words evolve and that he should get over it. > Should have asked him to draw up a Unix System for you then, Dave. Yup. It's more the how many boxes where talk how to other boxes doing what, but yes. >> Hate it when my vehicle breaks in the middle of dessert. At least it >> waited until the main course was over. > Make mine pie, thanks. >>>When I talked about the right conditions somewhere above, I was referring to >>>a damp/sweaty oily set of arms/fingers/wrenches etc coming into contact with [quoted text clipped - 5 lines] > Is this before or after pie? Mmmmm, pie... I thought the sponge was > outlawed? It's back, actually. Was on the new couple weeks ago. >>>As stated earlier, it's academic but hey at least we're all talking. >> >> My lips haven't moved a bit, actually... > Mine always do when I type. Bad habit, I suppose. Gotta have some of those, after all... > So, my take-aways are to never touch a car battery before (or is it > after) having pie or if on the sponge. ;-) There's a joke to be made with the words "pie" and "sponge", but damned if I'm gonna be the one to do it. >>> My title is "Unix systems architect", says so on the business card and >>> my job description. I had one particular person who was a [quoted text clipped - 40 lines] > There's a joke to be made with the words "pie" and "sponge", but damned > if I'm gonna be the one to do it. Always had trouble with those single leter/double lettter words... can we post stuf about SAB again now? All >>>>My title is "Unix systems architect", says so on the business card and >>>>my job description. I had one particular person who was a [quoted text clipped - 46 lines] > > All hehehe... sure, so long as we can work some pie into it... -Fred W
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