Hard Start When Cold 91 vert
Thread Starter
Pro
Joined: Nov 2002
Posts: 665
Likes: 2
From: Southington CT
Hard Start When Cold 91 vert
1991 vert auto, stock 90K, is hard starting first start of the day when it's cold. Starts up the rest of the day easy. Also mpg seems to be in the low 20's at best on the highway.
Parts replaced: spark plugs, air filter, wires, timing checked, fuel filter,
I have researched this topic on the forum and it seems to speak mostly to hard starting when hot suggesting leaky injectors. Any help would be appreciated.
Parts replaced: spark plugs, air filter, wires, timing checked, fuel filter,
I have researched this topic on the forum and it seems to speak mostly to hard starting when hot suggesting leaky injectors. Any help would be appreciated.
Instructor
Joined: Nov 2003
Posts: 102
Likes: 0
From: Fountain Valley CA
Had the same exact problem with my 89. Turned out to be the ECM.
It was not converting the temp. sensor input correctly, thus not pulsing the injectors for a rich start-up mixture. You're on the right track with using Datamaster to scan your ECM. I used WinALDL with the AKM cable cause DataMaster wouldn't work for me; even took the car down to the company and had them try to work it. No dice; something about baud rate.
It was not converting the temp. sensor input correctly, thus not pulsing the injectors for a rich start-up mixture. You're on the right track with using Datamaster to scan your ECM. I used WinALDL with the AKM cable cause DataMaster wouldn't work for me; even took the car down to the company and had them try to work it. No dice; something about baud rate.
Thread Starter
Pro
Joined: Nov 2002
Posts: 665
Likes: 2
From: Southington CT
thanks 89C4, I may try WinALDL because I'm not getting Datamaster to work for me either. Tried 2 computers and the data is not being "recognized". Did you get WinALDL to work before you replaced your ECM? Also what's involved and what's the cost of replacing the ECM? Thanks 89C4.......
Racer
Joined: Aug 2004
Posts: 417
Likes: 0
From: Audubon PA
I would go with Morley and check the fuel pressure first. All you need is a Fuel pressure gauge, connect it to the valve on the fuel rail (Passenger side), and when you turn ignition to first click without starting it (prime Ing) you should have 42 to 44 psi and it should hold there. It will go down very slowly, my 89 will hold 42psi for 15 minutes before it slowly goes down. As far as the ECM goes, you can get one from NAPA for about $100 and it's easy to get to but alittle tight under the passenger side dash. Take down lower dash cover and it sits staight upright, unscrew two bolts and it comes down then unplug it. Remember to transfer your PROM (chip). But before you do that check your fuel pressure. jzvette
Thread Starter
Pro
Joined: Nov 2002
Posts: 665
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From: Southington CT
thanks for the suggestions and information. I will check the fuel pressure next. I'm still and unable to get data using datamaster or winALDL. Could this suggest a problem with the ECM?
Instructor
Joined: Nov 2003
Posts: 102
Likes: 0
From: Fountain Valley CA
The WinALDL is a free download, but the cable cost me $90. It worked the first time I used it; the main reason I got it was to scan the ECM to check what it was seeing as far as coolant temp was concerned. I knew I had a temperature-injector pulse rate problem but I wanted to be sure.
BTW, one of my first troubleshooting step was to check fuel pressure like the others suggested. But you mentioned that it starts up easy the rest of the day, so I ruled out leaky injectors and fuel pressure.
If fuel pressure checks out ok, and, on your next cold start, try spraying starting fluid into the plenum; if it fires right up, for sure you have a lean mixture problem.
Good luck.
BTW, one of my first troubleshooting step was to check fuel pressure like the others suggested. But you mentioned that it starts up easy the rest of the day, so I ruled out leaky injectors and fuel pressure.
If fuel pressure checks out ok, and, on your next cold start, try spraying starting fluid into the plenum; if it fires right up, for sure you have a lean mixture problem.
Good luck.
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Thread Starter
Pro
Joined: Nov 2002
Posts: 665
Likes: 2
From: Southington CT
I picked up a pressure gauge from Sears and 1st checked pressure with just turning the key on. Pressure immediately climed to 42psi and then in less than 30 seconds dropped to 5psi and then to basically zero in less than 60 seconds.
Then the car was started and pressure was pretty steady at 35psi. Only ran the car briefly to get these readings. Are my injectors shot?
Then the car was started and pressure was pretty steady at 35psi. Only ran the car briefly to get these readings. Are my injectors shot?
