Sierra dohc runing problems
#1
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Sierra dohc runing problems
Hi folks, got a 1990 sierra 2.0 twin cam with an annoying flat spot on acceleration, it sort of kangaroos when you accelerate through the flat spots, feels like something is restricting it.
Ive done plugs, leads, cap and arm, changed fuel filter, coolant temp sensor for the ecu, changed oil and filter, air filter. Had gunsons fault reader on it which flashes out all clear.
Anyone any other ideas what else i could check before i bin it n fit a pinto lol
Ive done plugs, leads, cap and arm, changed fuel filter, coolant temp sensor for the ecu, changed oil and filter, air filter. Had gunsons fault reader on it which flashes out all clear.
Anyone any other ideas what else i could check before i bin it n fit a pinto lol
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This is an injection model isn't it? Check injectors and earthing points and if it's got an air flow meter that can cause problems too, possible fuel regulator for bad fuel air mixture
#3
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the twinky don't have afm's
one of the common problems as they get older is the crank case breather valve under the exhaust manifold, or the pipe that links this to the inlet manifold around the back of the engine letting air into the system
it could also be a short in the tps, but you need to have the correct tps and then there's a specific way to refit and reset the base idle etc so it's not as simple as just undoing some screws
one of the common problems as they get older is the crank case breather valve under the exhaust manifold, or the pipe that links this to the inlet manifold around the back of the engine letting air into the system
it could also be a short in the tps, but you need to have the correct tps and then there's a specific way to refit and reset the base idle etc so it's not as simple as just undoing some screws
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Thanks, will give those things a check, i know the pipe to the map is good tho
Had it a run earlier n noticed its not so bad when engines cold?
Might try venting crancase to atmosphere n block the port on the inlet to rule that out.
Guess the crank sensor could be breaking down when its hot but it starts fine hot or cold ?
Cheers
Greg
Had it a run earlier n noticed its not so bad when engines cold?
Might try venting crancase to atmosphere n block the port on the inlet to rule that out.
Guess the crank sensor could be breaking down when its hot but it starts fine hot or cold ?
Cheers
Greg
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Ok breather systems fine, crank sensor plugs fine with no oil in the connections, checked spark plugs and they look a bit on the lean side (white) guessing it must be fuel pressure related, the regulator has never been tampered with, wondering if it could be a weak pump? Also does anyone know what the inline filter looking type thing is on the return line for the fuel?
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#11
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I'd check the fuel pressure when hot too.
Seem to remember a rubber pipe in the in-tank pump either splitting/ collapsing on these..back in the day.
Seem to remember a rubber pipe in the in-tank pump either splitting/ collapsing on these..back in the day.
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Ive unplugged the coolant sensor and plugged another sensor in but just left it hanging on the wire so engine always thinks its cold, runs ok this way, will do for now until the pinto goes in
Cheers
Cheers
#14
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the pinto's can be tuned for more power far more easily and cheaply than the twinky can glenn
although the twinky is much better fuelwise each to their own
it's very hard to get bits for the later engine and your looking at around a max of about 140 brake with filters and chips and cams, or you can transplant the 2.3 engine in and as long as you've got aftermarket ecu's doing the ignition it's all good for around the same sort of money
or you can turbo it
although the twinky is much better fuelwise each to their own
it's very hard to get bits for the later engine and your looking at around a max of about 140 brake with filters and chips and cams, or you can transplant the 2.3 engine in and as long as you've got aftermarket ecu's doing the ignition it's all good for around the same sort of money
or you can turbo it
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they all came with 16v pistons though but the dohc was very very good on part throttle cruising, I've had 72 mpg from mine in the past and 40mpg is easy enough to get from them if they are looked after properly
They were designed to run hit though to maximize the economy but changing the fan switch to the Mondeo diseasal doesn't seem to effect that when it drops the fans by 10 degrees on each fan operation
They were designed to run hit though to maximize the economy but changing the fan switch to the Mondeo diseasal doesn't seem to effect that when it drops the fans by 10 degrees on each fan operation
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Ok folks ive fitted the pinto engine now and the car has the exact same problem, guessing it must be the fuel pump as this is the only thing that hasnt changed in the conversion, i've got a fuel pressure gauge on order
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I was fitting a pinto anyway mate, just hoped it would cure the fault in the process, once its running properly i'm doing a budget turbo conversion, thers more info online and parts available to suit the pinto on this conversion than there is for the dohc unit, as you say tho its a step back in time i know
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Haha, right i've fitted inline fuel pressure gauge today and its running 29 psi, drops slightly when u rev up, tried removing vac line from the reg which i believe should increase the pressure at idle? And nothing happens, also tried crimping return line and pressure still stays same, pressure drops instantly when you switch off. Defo seems like the pumps pumped!
Am i correct in saying the pressure should be 2.5 bar? (36 psi)
Am i correct in saying the pressure should be 2.5 bar? (36 psi)
#24
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Delivery pressure 5.0bar
System pressure 3.0bar
Regulated pressure with vacuum 2.3 - 2.7bar
That's from Autodata, seems a bit odd, usually you get slightly more pressure without vac..
Even so, if yours is 2 bar, it's lower than above spec.
System pressure 3.0bar
Regulated pressure with vacuum 2.3 - 2.7bar
That's from Autodata, seems a bit odd, usually you get slightly more pressure without vac..
Even so, if yours is 2 bar, it's lower than above spec.
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Thanks for the figures mate, yep the pressure should defo rise when vac is removed, it doesnt so i'm positive pump is on its road out
Cheers!
Cheers!
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Got a replacement used pump now, ive removed the inline fuel damper from it as the seals look a bit iffy, guessing this could be the prob with the pump thats in it at the moment? Will removing this have any effect on how it runs? Its obv for the dohc engine but does the pinto need one?
Cheers
Cheers
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