98 v70: fail to start when cold

Post by **CIK7** » 18 Oct 2023, 07:51

This viewtopic.php?p=620548&hilit=crank+cold#p620548 is the thread I have been reading mainly, with another one on a 99 model. My car needs extended cranks, but wont start on 1st try (normally minimum of 3 tries), when cold temps come around. This same issue happened during last cold season too. The engine will start on first try during warmer (>50F) temps. I thought I had made a thread about it, but searching my profile turned up zip. Robert does not mention 'cold temp' starts in his 'top 5 no start' video.
I typically buy any and all parts listed to knock out the issue quicker, but this time I dont have that money and want to get the right parts. Different people have said replacing the coolant temp sensor, cam position sensor, fuel pressure regulator, fuel pump relay, or fuel pump has solved their cold-temp no-start issue. Previous owner replaced cam position sensor 11/22 but issue persisted. I have replaced the fuel pump twice (once 2021, once start of 2023) but issue persisted. Plugs, wires, and dist cap/rotor were replaced within last 15-20k miles.
Will a 99+ fuel pressure regulator work on 98? Ill swap fuel pump relay if I can find one. I can buy a new coolant temp sensor if I must. Compression should be fine because the engine mostly holds the car in 1st on a hill; there is occasionally a slight movement. Is that an oxymoron?

Post by **Chuck W** » 18 Oct 2023, 09:06

The coolant temp sensor would be a good place to start. Checking the connector for corrosion, as that causes issues too.

The FP relay will also give you cold-start fits.

454cid · Post by **454cid** » 18 Oct 2023, 10:27

Do you have a way to check what the ECM is receiving from the CTS? Comparing what the CTS reads and the actual temperature should be helpful in determining if there is an issue there.

Post by **CIK7** » 18 Oct 2023, 13:42

Codes and live data attached. I wiped all dtc when finished reading the scanner. The temperature read as 160F going up while running. I thought there was 1 red relay on this car (fuel pump, red red with green). Turns out there are 2 and I have the wrong one (intermittent wiper? red with dark red). I have a mis on #4. I heard something about #4 being a common issue on these. Am I correct and, if so, what was that issue?

Post by **CIK7** » 18 Oct 2023, 14:35

How risky is it to use a cheaper aftermarket fuel pump relay like this? Will it even fit with the factory plastic side slot pattern?https://www.ebay.com/itm/352527206747?f ... R_jL1MfoYg

Post by **scot850** » 18 Oct 2023, 15:10

Did you try jumping the relay to see if it makes a difference before buying a new relay?

Neil.

Post by **CIK7** » 18 Oct 2023, 17:14

scot850 wrote: ↑18 Oct 2023, 15:10 Did you try jumping the relay to see if it makes a difference before buying a new relay?

Neil.

I did not test or buy a new one yet. I assume you mean putting a bridge from bronze to bronze and silver to silver in the socket, right?

Post by **CIK7** » 18 Oct 2023, 17:43

Besides your input, something tells me I need a new coolant temp sensor... Joking aside, I am surprised I failed to notice this until now considering that I try to keep the car shipshape. I look in the engine bay every few days for one reason or another.

Post by **scot850** » 18 Oct 2023, 18:38

This thread is a great resource for P80 no starts from cn90:

viewtopic.php?t=52252

In there he lists the 2 pins to jump in the relay seat to get the pump to run continuously. It is pins 15 and 87.

Neil.

Post by **CIK7** » 18 Oct 2023, 20:30

scot850 wrote: ↑18 Oct 2023, 18:38 This thread is a great resource for P80 no starts from cn90:

viewtopic.php?t=52252

In there he lists the 2 pins to jump in the relay seat to get the pump to run continuously. It is pins 15 and 87.

Neil.

I have the jumper ready in the passenger seat. Tomorrow morning, I will install it and report back the result. This car has to start because Im taking it to a dr appt in Paris and I want to take advantage of the cheaper premium gas while at Walmart.