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  #1  
Old 08-12-2006, 03:46 AM
johnnybp7 johnnybp7 is offline
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Default Engine Problems

How's it going guys/gals,
Me and my good friend recently purchased an 87 Grand National for $100.00 and it's in pretty good shape, but it's got one problem that we can't figure out. I'm not even sure where to start looking so I figured I'd post here to see of someone could shed some light on the problem. Basically the cars idles relatively smoothly but if you listen carefully you can here the engine missfire, it's also very slow at reving when you floor the gas, the boost is also not building at all. I know the info isn't the most descriptive but I'd be more then happy to give more info if I knew where to look. Any help would be greatly appreciated.
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Old 08-12-2006, 09:19 AM
JHensberry JHensberry is offline
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Default Re: Engine Problems

are you sure it has a turbo, not just a clone car? after all it was only $100
how old is the coil pack/ign module?
ohm out the coil pack per instructions on website.
try to get a scantool to help diagnose any further problems.
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Old 08-12-2006, 02:13 PM
johnnybp7 johnnybp7 is offline
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Default Re: Engine Problems

It defiantly has a turbo, the pervious owner replaced it with a brand new one thinking it was the cause of the problem, as far as a know the coil pack and ignition module are the original ones that came on the car, we also have a Scanmaster tool so I'll get all the readings from the coil pack and from the scanmaster and post back to let you know.
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Old 08-12-2006, 02:53 PM
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Lightbulb Re: Engine Problems

Quote:
Originally Posted by johnnybp7
coil pack and ignition module are the original ones that came on the car
Does the coil still have a date sticker on the top? Or a sticker with "turbo" on one end? If so, that is a ~20 year old piece. Both coil and module may be a bit weak or in poor condition at this point. The bad news is that it may cost more to replace them than you paid for the car.

I would also check to see that you have a free flowing exhaust. The catalytic conveter (if still equipped) may be plugged up and restricting exhaust flow. That would hinder boost production.
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Old 08-14-2006, 02:34 AM
johnnybp7 johnnybp7 is offline
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Default Re: Engine Problems

Ok, I got the scanmaster readings today from the Grand National so I'll list them as to the order they appear in the menu:

Start up screen was at I believe 940 and 00 on the other screen but it droped to 410 after it warmed up

AF was at 07
L8 was at 46
int was at 128
bL was at 150
CLt was at 131
Ats or At5 (not sure what digit it was) was at 82
r was at 875
tPS was at .46 at idle, I didn't get a full throttle reading but I can
IAC was at 60
cc was jumping up and down but I saw it go as low 01 and as high as 283
I believe
that's all the readings I got off it

Last edited by johnnybp7; 08-14-2006 at 02:35 AM. Reason: wanted to change the wording
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Old 08-14-2006, 06:44 PM
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87geeinn 87geeinn is offline
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Default Re: Engine Problems

The numbers look alright, however it appears as though you took the readings before the car was actually warmed up. "Clt" is your coolant temperature, and assuming the coolant temp. sensor is working, the car should run at least 160-165* IF it has a 160* thermostat in it. The stock thermostat is a 180-185* piece so it may run even warmer if the thermostat hasn't been upgraded. The rest of the numbers look as though they should and the car "seems" to be doing what it normally does at idle.

Now...when you say it doesn't build boost, you don't mean with the car sitting in 'Park' do you? The car won't build boost unless under a load and you shouldn't rev the car like that when it's not under load.

You might wan't to start with a chip upgrade from www.turbotweak.com . You'll be surprised how many issues a simple chip can fix. After, that you need to check, as mentioned earlier, the ignition components and also the fueling system (i.e.-injectors, fuel pump, presence of a hotwire kit).
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Old 08-14-2006, 06:54 PM
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Exclamation Re: Engine Problems

Quote:
Originally Posted by johnnybp7
bL was at 150
Maybe your car has its Block Learn at 150, but mine sure doesn't. That's at the extreme lean end of the scale. Might indicate...well...a variety of problems.

Read http://www.gnttype.org/maint/quickref.html and all related pages.
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Old 08-14-2006, 07:58 PM
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Default Re: Engine Problems

x2 on the BLMs. Skimmed over and missed that. Could be a simple as throttle seals leaking badly, cracked intercooler/up-pipe hoses or a PITA problem such as a large crack in one of your headers.
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Old 08-15-2006, 04:17 AM
johnnybp7 johnnybp7 is offline
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Default Re: Engine Problems

Just out of curiosity what are the symptoms of a blown head gasket(s), it's really odd, we've swapped out the coil pack and ign module and it made a little difference but especially when the cars fully warmed up it shakes pretty bad as if it's about to stall, also there's not boost, like it doesn't even try to spool, my buddy put it in drive and tried to hold the brakes and give it gas, you can see the engine moving from the stress but it's like it just doesn't have power.
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Old 08-16-2006, 02:12 AM
johnnybp7 johnnybp7 is offline
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Default Re: Engine Problems

Anyone? I have a bad feeling the head gasket(s) are gone, but I have my fingers crossed that's it's not the case, there's really only a few things left for me to try, spark plugs, new plug wires, ECM and fuel injectors, does anyone know of a good how-to-guide about replacing the head gaskets on these cars. Also if i do need to get new injectors I'm planning on upgrading a little, I know a TA-49 turbo is going in sometime soon so I was wondering what injector would be a good choice. Any help would be greatly appreciated.
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